Yep, the Saturn sank Sega. I get that a lot of retro collectors do enjoy it. Still doesn't escape the fact that it was an awful system even when it was new. Ugly graphics (even for the time), difficult to program games for, botched surprise launch, no Sonic. If you weren't into 2D fighting games and spaceship shooters, there was just no point in having one.
Sega's success against Nintendo during the early 90s is what convinced all those companies to grab a piece of the pie. Of those, only Sony really understood why Sega had done so well in the first place. Which is why they're still around today.
I think history has proven that there's only room for three consoles, with one always being the dominant system. The only real secret to it is giving gamers what they want.