Oddly enough, there is really only one thing stopping somebody from doing this - armament. It is hard coded in RB and cannot be changed. There are, at maximum, two forward firing machine guns of .303 caliber. No cannons and no multiple banks of machine guns.
For the rest (within the limitations of RB):
3d model - Possible
FM - I believe RB can handle a WWII FM
Skins - Possible
DM - Possible
Map - you would have to close your eyes and make believe
Would it be anywhere near as good as IL2? Almost certainly not, as IL2 had a much more sophisticated FM and DM engine. Is anybody going to do it? Doubt it. It would take alot more than new bitmaps. There would have to be all new FMs, DMs, and 3d models too.
P.S. Not sure if it is possible to model an enclosed cockpit in RB either.