Nintendo produces quality games, and I'd never want them to have to answer to other companies about when they come out. If they were a third party, don't have any illusions that Sony or (in this case) Sega would let them have as much time as they want. I'd rather deal with slightly antiquated hardware and get great games out of it.
If Sega kept in the console business, we'd have two things. A likely great console with mediocre fist party games and not enough money to buy exclusives.... and... no Microsoft. I've always rather been under the impression that MS entered because Sega faltered. Would they have launched in a market with THREE consoles? Unlikely.
So... really, I'm happy with where we are. Nintendo, though still

ing goofy with their hardware, is making amazing games. Microsoft stepped up to become what Sega SHOULD have been, but never would have acheived. Sony is continuing to be Sony.
Sega was NEVER good at business. NEVER. Genesis add-ons, Saturn, too early Dreamcast with no EA support. They were interesting innovators, but they were terrible at running a business. If it wasn't the Dreamcast, the next one would've sunk them anyway. Shame, too, because the DC is still my favorite console ever. I, however, have no faith that Sega would've been able to continue like that.