Not many people have 4k sets, HDR isn't standardized, and by the time things get sorted out and these end up in peoples' homes, the next generation will be upon us and ready to fully exploit 4k. As it is now, both of these consoles will be struggling to do 30fps at 4k, much less 60fps like people want to see.
These are stop-gap consoles and as such should focus on enhancements that can be appreciated at 1080p like 60fps and additional geometry.
And I don't think this is the start of a rolling console hardware future, which would force console manufacturers to stick with particular APU vendors and perhaps be hamstrung when it comes to compatibility that would allow for hardware iterations.
Anyhow, the Scorpio, MS's console, is still a year away and the PS4 Pro is launching this November, there will be a year head start and all that press going to Sony, anyone trying to wait will have a hard time ignoring all the enhanced games.
When MS's offering is here we will already be 4 years into the current generation, and the gap between Sony and MS would have an additional year to grow. All the games for these stop-gap consoles will have to remain compatible with the older hardware, so we can't really stretch things out to another 8 year generation again.
The fact that Scorpio is a year away makes me think MS were caught with their pants down and are scrambling to have an offering, but I don't think it will have much of an impact before we start hearing about the PS5, which Sony has stated is an eventuality.