A reduction in the temporary degree of disability should not affect your RE payments. The only way it would is if there was a significant change in your disability to the extent that you could be working more, e.g. a finding that you can work 8 hours a day, whereas you currently limited to four hours a day. This would be unlikely, as your schooling and job are full-time, especially when combined.
What may be more of a problem is the possibility of an SLU opinion. If the IME believe you have reached maximum medical improvement, are stable, and can be found to have a permanet loss of use of the foot/leg, then the carrier can argue for the award of that schedule, and limit their future payments. For instance, if the IME said a 50% loss of use of the leg, that would equate to 156 weeks of compensation. If there is no protracted healing period, that would be the maximum benefit the carrier would be responsible for paying if the SLU were implemented.
As soon as you receive the IME report, make an appointment with your attending to review the IME opinion. Your doctor may disagree with any opinion of an SLU, as it sounds as though he does not see you as being at MMI, but rather is contemplating a future surgery. In addition, if there is an instability, or continuing pain syndrome, those are reasons to not do an SLU, and rather do a classification.
That being said, if you expect to get a job when you graduate which will pay well, and exceed your AWW, there may be a reason to accept an SLU, as the payments would continue to the maximum number of weeks allowed by the SLU regardless of your wage level. If you are classified, and earn more than you AWW, there are no benefits due to you. Note that the medical continues in either case.
Talk to your lawyer. There is some strategizing to be done . . .