I think MIcrosoft kind of planned this. Now the PS4 has to at least match the One X is power, and I don't see components similar to the One X going down considerably in price unless a deal is made or PS4 doesn't release until 2020 or late 2019. By this time they'd have to either release a 450+ console, or something weaker than the One X at a cheaper price, or like I said earlier, they'd have to have one hell of a chip deal with AMD. But let's be honest, PS5 has probably already neared the end of development and specs would have to be based on 2016-late 2017 or early 2018 tech.
This is a really strange position for the PS5 to be in and if they really don't want to ignore the Nintendo Switch, and implement a portable option, then prices shoot through the roof as mobile chips the power of Xbox One X don't exist, and if they do they aren't in consumer electronics yet. I think their best bet is to sell a $450+ console and see where it goes from there. And considering One X isn't Microsoft's next console, it's just going to be really strange. Generations are already dead, this next "generation" will finish the notion of them off.
Be assured Sony has very close ties to AMD (they even developed some Vega features together)...if rumours are true that they’ll go for a dedicated GPU/CPU Solution this time, instead of an APU, a considerable increase of power is a given. PS5 won’t be in a strange position..X1X is, since it’s too expensive for a late mid-gen upgrade and won’t be able to keep up with true next gen titles.
Generations aren’t dead and especially not because of X1X, since no one really owns the thing to make an impact. Plus it’s lame CPU will prevent it from being relevant once next gen starts rolling.