"If the PS4 sells 100 million, consoles will become obsolete."
Is that to say that consoles will become obsolete if they don't start next-gen soon enough? Hm...
It's my opinion that something will need to change if console gaming is to stay competitive, as minor inconveniences are beginning to seem like major drawbacks when compared to competition that allows you to pick up and play a game anywhere. I can see products like Google Stadia taking a significant market share if all goes well.
The "wow" factor of a new generation of consoles is going to be mitigated by the early load blowing of the PS5 Pro and Xbox One X. They will need to rely more on new features and clever marketing than the strength of the console, unless they hold off until hardware is better (or sell a really expensive console).
I'm also very curious to see what Sony does to counter the Nintendo Switch.