Worst possible scenario?
This is pretty much it.
No idea if Wade's shoulder was able to be popped back into place cleanly, but if it is and there is no significant damage in there, then he can still come back for the home stretch of the season. The problem would be that his left shoulder would still be weak and prone to further injury. So given his style of play, it's doubtful he can return to his normal self.
Suddenly, the outlook is fairly bleak.
So what has to happen in the meantime?
Well, Shaq has to pretend like he's playing against Dikembe in every game. He was very aggressive and looked to have some explosiveness back against the Rockets. If he keeps that up, he'll command a double team more often and get guys open shots.
That means guys have to hit those shots to keep the offense going. Jason Kapono will get a lot more plays called for him now, so he'll have to get more creative to get shots off. That means his percentages will slip, but oh well. He has to remain a threat.
After Shaq, though, I think the most important guy to this team with Wade out is Jason Williams. The faster he can get himself back in game shape, the better for the Heat, because he can still create tempo and he can penetrate and draw the defense. Not nearly as often as Wade did, but at this point, anything will help.
Finally, the defense has to get down and dirty. The defense and Shaq have to define this team while Wade is out. That could mean ugly games, it could mean lots of fouls, but it's the best chance the Heat has to stay above .500 and get itself a playoff seed (any will do at this point, right?).
Personally, I think this team, with a healthy Jason Williams, is still a .500 team or better. And I don't think this means Riley will get desperate and make a silly move at the trade deadline because, let's face it, Dwyane Wade is not available via trade. And if Wade doesn't come back at full strength this year, a repeat title might be out of the question.