Roundtable: The fallout from Conor McGregor's announcement

Okamoto: Only a few options can replace McGregor at UFC 200 (2:10)

ESPN MMA writer Brett Okamoto gives the options for a potential replacement of Conor McGregor to headline UFC 200 in July. (2:10)

UFC featherweight champion Conor McGregor's sudden retirement announcement through social media rocked the sports world Tuesday.

McGregor (19-3), 27, who has yet to speak publicly on the matter, was pulled from his main event slot at UFC 200 on July 9, leaving the promotion to scramble to replace his welterweight rematch against Nate Diaz.

As we continue to walk out the implications of McGregor's decision on UFC 200 and beyond, our roundtable of experts shared their thoughts:

1. What's the best option for a UFC 200 replacement main event to maintain the same level of buzz?

Brett Okamoto: The best option would be Ronda Rousey, but I don't see her coming back before that November time frame she has already set. The second-best option would probably be bringing former welterweight champion Georges St-Pierre from his own "retirement," but alas. I also don't think that's realistic. If St-Pierre returns, I expect it to happen in the fall. So I believe very strongly that if Jon Jones comes out of Saturday's interim title fight against Ovince Saint Preux at UFC 197 healthy, and Daniel Cormier's leg heals in time, their rematch is what we'll see at UFC 200. Will the buzz for that fight match what Diaz-McGregor II would have produced? I'd guess not quite, but it won't be that far behind. If Jones loses to OSP? All bets are off.

Mike Huang: Brett mentioned in the video above that whispers of a St-Pierre return are possible, and I think something like GSP-Nate Diaz at 170 pounds could save UFC 200. Unless Diaz's own tweet about retirement was serious, too.

Reed Kuhn: UFC 200 is already stacked, and while it was expected that fans would pay close attention to a rematch between McGregor and Diaz, it was hardly the most important matchup on the card for the UFC's various title pictures. There are still two belts on the line, and a number of potential contenders fighting to hold their spot in the mix. From a buzzworthy standpoint, however, nothing could top St-Pierre-Anderson Silva (unless, say, Fedor Emelianenko got over his Octagon jitters and threw a gauntlet down at heavyweight champion Fabricio Werdum). The odds of either happening are very slim, especially since three out of four of these guys are currently booked for fights this summer, and GSP is another ongoing question mark.

Brian Campbell: One can only imagine the cries emanating from UFC headquarters of: "Help me GSP, you're our only hope." A Star Wars reference might be apropos in this case because it will take a star of McGregor's proportion to produce the same level of buzz. And with Rousey not expected to return until November, a St-Pierre comeback from a self-imposed three-year hiatus against current welterweight champion Robbie Lawler is the only option capable of exactly that.

2. In McGregor's absence, which fighter steps in to take the title of the UFC's biggest star?

Okamoto: In the short term, it's Jon Jones. Before McGregor and Rousey ruled 2015, there was Jon Jones. He's widely considered the best pound-for-pound fighter in the world and he's obviously polarizing. His legal issues last year (not that other fighters should try to mimic this), might actually make him a bigger star -- after all, everyone loves a comeback story. Jones walks a fine line between MMA icon and complete self-destruction and that captures people's attention. And of course, few are more fun to watch in the Octagon than Jones. He has the ability to compete in two weight classes. A future move to heavyweight is all but guaranteed.

Huang: I wish we could see Demetrious Johnson carry the load, but he's at the point of saturation. He has won so much that no one cares, and fans are not as interested in flyweights (which is a shame because they are so energetic and skilled). Johnson defends his title in the co-main event Saturday and unbeaten Henry Cejudo will test Johnson, but ultimately I think Jon Jones' return in the main event could buoy the UFC. McGregor's wheelhouse was his ability to attract both haters and fans. People loved him or hated him. But what that really means is double the audience. I think Jones has stepped over to play the role of the "heel" with his cavalier attitude and personal problems. Haters want to see him get his tail handed to him. Fans revel in his dominance. Either way, Jones will rise again.

Kuhn: If McGregor does walk away, it will be difficult to replicate his powerful persona combined with his dominance inside the cage. Only a few fighters can even enter the conversation on skill alone, and then they have to be able to pull off the attitude with style -- which can't be faked. Among the current lineup, only Jon Jones and women's strawweight champion Joanna Jędrzejczyk fit that bill. Rousey previously did, but a big loss does a lot to kill the mystique. Newly crowned middleweight champion Luke Rockhold has potential to dominate, while also displaying a persona that attracts fans.

Campbell: It's still Rousey the moment she returns in November. As devastating as her upset loss to Holly Holm appeared at the time -- to her brand and the UFC's bottom line -- Miesha Tate's dramatic title win against Holm leveled the playing field. Suddenly, the women's bantamweight division is red-hot again. And while fans first flocked to Rousey because of her image of invincibility, even more will connect with her newfound sense of humility as she attempts to regain all that was lost. It's Rousey's crossover potential to those who wouldn't normally watch the UFC without her there that allows her to trump Jones.

3. If McGregor never fights again, how do we rank him historically?

Okamoto: It's not easy to do this from a competitive aspect, for a few reasons: First of all, he really wouldn't have had a "full" career. No one retires at 27 while holding the "keys to the game," as McGregor likes to say. Comparing him to others who fought well into their 30s is a task. Secondly, there were so many odd circumstances surrounding many of his biggest fights. McGregor has fought eight times in the UFC. His opponents have been changed in half of those, several times at essentially the last minute. That makes it hard to put some of his wins (and his one loss) into perspective, because there were unique variables involved. I don't think you could rank him inside the top 10, probably not inside the top 20, either -- but if you're talking influence on the game? He's on a very short list for No. 1 all-time, in my opinion. McGregor has taken the sport to another level in the U.S. and Europe and negotiated paydays not seen in this sport.

Huang: McGregor's meteoric rise to greatness was as swift as his surprise exit. In other sports, when greatness was cut short by injury or early retirement (Gale Sayers, Bo Jackson, Bernard King), there's still some modicum of track record to judge. I think McGregor's got enough. But it falls short of any Hall of Fame consideration and certainly outside of any "greatest featherweight" or "greatest pound-for-pound" discussions. The UFC titles have been so fluid and interchanging the past two years that you can't compare any achievement to the runs had by Anderson Silva, St-Pierre or Matt Hughes. Perhaps McGregor was just "another" champion in this era of fluidity, albeit a very charismatic one.

Kuhn: McGregor was as aggressive in the ring as he was on the microphone. And when it comes to fighting in a cage, there's no more telling of a metric than "victories per fight minute," where McGregor ranks fourth all time. That's only behind Rousey, Royce Gracie and Don Frye, and ahead of legends like Vitor Belfort, Frank Shamrock, Andrei Arlovski and Frank Mir. His offensive striking stats were borderline ridiculous, and the emphatic way he finished opponents left little doubt that we were watching something rare and special. And while he's reeling from a loss now, the other "greats" of the UFC in the same ranks all had their own losses. He'll be remembered for the wins and epic rants more than anything.

Campbell: With just eight UFC fights in three years, McGregor's legacy is much more tied to his record-breaking ability to draw. His showmanship and trash-talking skills remain without peer, maybe in all of sports. But inside the Octagon, there's a feeling we never found out exactly how great he really was. What would have happened had Chad Mendes been provided a full training camp? How would the Jose Aldo fight have played out had it not ended shockingly in 13 seconds? McGregor shouldn't be docked points for the fact that his biggest wins produced just as many questions as answers. But we also can't ignore that.