No injuries is unrealistic. Assuming that we don't have TERRIBLE LUCK, we'll win 2/3rds of our games, like we have been as of late. So let's go with about 54 games... that's actually the number Hollinger predicted. Don't like him at all, but he can be right about these kinds of things.
But... we would also look like a title contender, IMO. Come playoff time, who would've stopped Nash, Kobe, Rejuvenated Pau and Dwight? I just don't see it happening. Even off the bench, we would've Hill back. We would have Clark. Blake is playing great. Jamsion is an X factor. And who knows when Meeks starts getting hot? MWP can score 20 if his mind is into it, too.
Realize the 2010 Lakers weren't all that athletic either. Neither were the 2010 Celtics. It was a Finals series of slow veterans. Age isn't that much of a disadvantage, IMO.