they wouldn't serve any purpose right now. We'd need a complete overhaul of the base capture system, the role aircraft and vehicles serve, our troop haulers (SdKfz 251/22, M3, Jeep, C-47, LVT), probably the strats, and perhaps even the 'map win' system. Our enviornment would need to be updated as well, with the inside of buildings modeled, and a pelethora of new objects added.
And thats on top of all the modeling they would have to do for each individual infintry weapon, and the troops themselves.
All in all, its a MASSIVE project, and one we probably won't see any time soon, if at all. It really would have worked better if HTC had started with infintry as the core of the game.