Sure, and thats fair but also think of the whole way this is presented to US, the consumer. Sakurai is arguably presented as the "be all end all" of this franchise, why? Because for one the team assigned to the project is being kept in secret and #2, its easier for the consumer to relate one game to one person. Mario to Miyamoto, Gunpei Yokoi with Metroid, Iwata with Kirby ... Sakurai has become synanimous with Smash, whether e likes it or not, really. I could very well see Sakurai naming somebody as HIS successor after this whole ordeal is done, for us its hard to tell because the only man we know that works on the game is THIS ONE GUY, Sakurai .. so really well have to wait and see.
Also, so what if he leaves? Sure the game may be worse, but itll still sell a shitload, I mean just look at Mario Party 8, subpar game but damn its outselling all the previous ones. Were hardcore and would be saddened if people we respect werent invoved in the game, but the general audience has no fucking clue and they will buy Smash just based on the fact that they liked the previous one.