Well, that's just the way it is when not only the technological but also the political will is there.
There will certainly be some headaches and alarm bells ringing in the USA, but at the same time we don't know how far NGAD is.
It may be that they are at a similar stage, or even further.
But in my opinion, two things will soon be achieved.
It could well happen that they now export Chengdu J-20s and J-35s more actively in the next 2-3 years.
This could mean a fundamental shift in power in some regions of the world, particularly in some critical countries in South East Asia and the Middle East and North Africa.
It could well be that the US is no longer forced to sell the F-35 so restrictively (only NATO and close allies) but would be forced to relax it massively.
For China it is a win to win situation as they would be more willing to transfer technology for the GEN 5 aircraft, the USA would be under great pressure to make a move if they offer something to country XY.