Alas this is one of those things that changes nothing big.
The Saturn was doomed for a huge number of other reasons, managing to push out a proper Sonic game would have at best with very high review scores (yes, there are academic studies on exclusives impact on console hardware sales if anyone besides me is interested) shifted a few hundred thousand extra Saturn systems.
Perhaps Sonic Adventure is butterflied, but again without greater changes Sega is still doomed to exit the hardware market. Maybe the Sonic games all turn out really good going forward, giving Sega a little extra cash/cachet particularly on Nintendo platforms and making them a major 3rd party publisher... but Sega was terribly run too, so it really is hard to go somewhere with just this as a POD.