The source said the injury could keep Kane, who was injured in the first period and did not return, out of action toward the "higher end" of the estimate. He was placed on long-term injured reserve, which means he must sit out at least 24 calendar days and 10 regular-season games.
The regular season ends April 11, and the playoffs begin the following week. That could mean Kane misses the start of the playoffs if it's closer to the 10-week period.
Kane was cross checked in the lower back by the Panthers' Alex Petrovic at 7:49 of the first period. The force of the hit knocked Kane to the ice and drove him into the boards. He was slow to get up and was bent over as he skated to the bench. He immediately departed for the locker room.
"Looks like he might miss some time, but we'll know the extent of it tomorrow," Blackhawks coach Joel Quenneville said after the game.
Petrovic, who was given a two-minute minor penalty, is not scheduled to have a disciplinary hearing for the hit, a league source told ESPNChicago.com.
"You get ticked off when the best player in the league gets hit like that," Blackhawks forward Kris Versteeg said. "I can't totally comment because I didn't fully see it. You never want to see that. People pay a lot of money to watch Patrick Kane play. It's never good when he's out of the lineup -- not only for us, but for the league. Hopefully, he's good. We'll see how it goes."
Kane is tied for the NHL lead with 64 points and leads the Blackhawks with 27 goals and 37 assists. He has not missed a game this season.
The Blackhawks are third in the Central Division with a 36-20-5 record and 77 points. They trail the Nashville Predators by 12 points and the St. Louis Blues by three points, and they are ahead of the Winnipeg Jets by four points.
"He's 20 to 30 points ahead of the next guy on the team," Versteeg said. (Forward Jonathan Toews is second on the team with 49.) "That's hard to replace that scoring. This team always seems to find ways, so we're just going to have to do that. Dig deep."
The Blackhawks were without Kane for the final 12 regular-season games last season because of a knee injury. He has remained healthy for much of his career and hasn't missed more than 13 games in any regular season in his eight-year career.
"I don't think you can replace the things that he does with the puck, without the puck, the attention that he draws, but one of the strengths of the organization is depth," Blackhawks forward Patrick Sharp said. "You hear it all the time: When a player goes down, you need to step up and collectively fill those shoes. But you guys know as well as I do what kind of player Kaner is."
The Blackhawks recalled top prospect Teuvo Teravainen from the Rockford IceHogs of the AHL on Wednesday.
Teravainen, 20, has two goals and two assists and is a minus-1 in 15 games for the Blackhawks this season. He has nine goals and 16 assists and is a minus-6 in 39 games for the IceHogs.