Michael Jordan didn't succeed in baseball. He was only a bench warmer in the MINOR League. Rossi doesn't seem to believe in such a thing. Besides, he'll be switching to just a different kind of motorsport. He himself admitted that racing cars are his real dream. It just turned out he was so brilliant in motorcycles as well, but he still wants to try out 4 wheels. Mario Andretti was also successful in various kinds of racing, which may have added to Rossi's inspiration to give F1 a shot.
It would be really nice to see him triumph here. If he makes a good impression in Ferrari, he'll probably replace Schumacher once and for all. If he doesn't succeed, there's always a bike waiting for him.