The Heat are a better team when Wade doesn't play because Lebron doesn't defer and just takes over (the Heat is 5-0 without Wade, 5-4 with Wade this year). When Wade plays he just gets in Lebron's way and the team is worse on the whole. And lets face it, the Heat go as Lebron goes, and will as long as Lebron is on the team.
I don't actually think they will trade Wade, but I would certainly be looking at it if I'm Pat Riley and would certainly call the Magic to see if they would swap Wade for Howard.