I think Atari would still be around today. (Not the 'NEW' Atari, that activision have resurrected)
But Atari would've survived longer and everyone would have had to buy an ST/E.
But then on the other hand, the PC might have taken hold and we could have listened to games with pc speaker beeps a lot more.
I don't think the console world would have changed that much (if at all). Maybe a few more megadrives sold here and there.
So there you have it, my completely useless view, where I've managed to not commit to saying anything.