Of course, losing Bosh isn't the same as say losing Lebron or D-Wade, but make no mistake, Bosh's absence undoubtedly gives the Pacers a better chance in this series. Talent-wise, the Heat still more than enough to handle the Pacers, but losing the 6'11" Bosh, a versatile power forward who can give the Pacers' big men trouble at both ends of the floor, will be particularly damaging to a Heat team that is already limited in size.
Roy Hibbert was often drawn out of the key by Bosh's mid-range game, and struggled to keep up with Bosh's speed off the dribble. Without Bosh, the Heat have to throw a combination of Joel Anthony, Udonis Haslem and Ronny Turiaf at Hibbert, and none of these guys are over 6'10". If Hibbert doesn't take advantage of that, then the Pacers absolutely deserve to lose.
On the other hand, losing Bosh means we'll see a lot of Lebron at the four, which could be bad news. As we already know, Bosh sat out the entire second half of game one, and yet the Heat outscored the Pacers by 15. But I'm of the opinion that the sample was too small to take too much out of it. Over the course of the next few games, Bosh's absence will be felt, and it's up to the Pacers to utilize that to their advantage.
One other point: if Lebron is moved to the four, does that mean Granger won't have to guard him as much? If so, that could help Granger's offensive game. He's going to need all the help he can get too, considering he went 1-10 in game one.
Losing Bosh most probably won't be enough for the Pacers to overcome the Heat in this series. Their probability of winning probably went from something like 5% to about 15 or 20%, which makes it slightly more possible but still highly unlikely. The biggest beneficiary will probably be the teams the Heat play next after the Pacers (assuming they get through as expected), as Lebron and Wade will have to carry a much bigger load while Bosh is gone, and that will eat into their stamina in the later rounds. I'd like to think that if the Heat missed out on a title again this year, people will say that the Pacers had something to do with it.