Personally I see no negative effects from Amare's return, indeed, the Suns are probably chomping at the bit to start taking advantage of a siginifcant post presense, one their opponents must respect If the transition into more half court sets is smooth and is accomplished by the end of the regular season, this team should be lethal in the playoffs, where the action slows down anyway and where you must have a post threat or you go home. Amare is that serious post threat, not a back to the basket type as 'Koast pointed out but more a motion threat coming off screens, give and go's, and Nash's spectacular passing ability. None of this really should affect the freeflowing offense the Suns run very much anyway.
Additionally, Phoenix really seems to buy into the team concept, not a lot of ego's there to disrupt chemistry, sort of like the Spurs. I think they all realize if they are to get deep into the playoffs, they need Amare back and contributing, I also think they are all perfectly OK with that.
Look out San Antonio, these guys could clock you if the above scenario's play out and you don't take them seriously, I know the Mavs don't have enough to match up with them.