"I would assume it would be a while; I would assume it would be a significant amount of time,'' Rhule said Saturday. "I'm pretty sure it will be a long-term injury.''
Corral suffered the left foot injury in the Friday night preseason loss at New England.
A 2016 study in the American Journal of Sports Medicine determined NFL players with Lisfranc injuries treated without surgery missed an average of 6.2 months recovering and those who underwent surgery missed an average of 11.6 months. Rhule said Corral, his family, agent and team doctors are exploring the best option.
In terms of the starting quarterback battle between Baker Mayfield and Sam Darnold, Rhule still wasn't ready to name the winner, although multiple sources have said the job remains Mayfield's to lose.
Rhule also wasn't ready to say whether he would make that decision before the preseason finale Friday against Buffalo, but he did say "most, if not all, of the starters'' will play against the Bills.
Almost all of the starters, including Mayfield and Darnold, were held out of the 20-10 loss to the Patriots.
Rhule said Corral's injury won't influence his decision on who plays against Buffalo. But he said it could influence whether the team keeps three quarterbacks as he said was the plan early in training camp.
Corral likely would have been the third quarterback, behind Mayfield and Darnold. Carolina also has former XFL star PJ Walker, who is 2-0 as a starter for the Panthers the past two years.
Walker struggled with two interceptions and a lost fumble that resulted in a touchdown against New England.
"That position takes a beating,'' Rhule said. "We want to have as many good players at that position as possible and make no apologies for it. Matt was coming along.''
Corral's injury occurred in the fourth quarter when a player stepped awkwardly on his foot. He limped off the field and did not return, leaving Gillette Stadium in a walking boot.
Rhule said deep snapper J.J. Jansen and other veterans gave up their seats in first class to give Corral more room on the flight home.
"I hate it for him,'' Rhule said of Corral. "I thought he was playing well, too.''
The Panthers selected Corral in the third round out of Ole Miss. In the Friday matchup he saw his most extensive playing time in practice or preseason games as Mayfield and Darnold have gotten a majority of the snaps.
Corral, who was 1-for-9 in the preseason opener at Washington, was 9-for-15 for 58 yards against New England.
"I thought I saw a lot of really nice signs early in the game,'' Rhule said. "But I know Matt's a battler. This year's developmental. He's just going to have to grind, both taking care of his foot and all the things he needs to do as a quarterback.
"Hopefully, someday he'll look back and say it was a blessing, but I hate it for him right now.''