It's hard to say what anybody would have done, but I just can't imagine a struggling Larry Bird following Magic to the Lakers, or a titleless Jordan deciding to join the Rockets to try to win a championship.
I don't think any of those guys could have dealt with being a co-equal to chase a ring; all of them had the competitive drive to be "the man", even alongside great teammates. I mean, Kevin McHale goes for 56 points to set the team scoring record, and Larry tops that 9 days later by scoring 60. These weren't guys who could accept being second best.
I understand Lebron's decision. He's making a ton of money, playing in a great city alongside guys he considers good friends, for an organization that he respects. However, I do think he's damaged his legacy a bit. He'll always be seen as a great player, but I don't think he'll ever reach the Michael/Magic/Larry upper echelon. I don't think Lebron will ever surpass Larry as the best SF of all time, and he won't supplant Kobe as the best player of the post-2000 era. He had a chance to do both, but I think that's gone now.