First of all, you said it like China is not already in problem.
Chinese population is in decline at a rate even worse than Russia. Economy is not growing at double digit, and replacement market is now emerge in other SEA/SA country. Unless you are a die hard Chinese fans, you would see a downward trajectory to a tune of the next 2 to 3 decades as the other Asian nation catches up. You can't expect China to grow at a rate people seen between early 2000s to early 2010s
NATO, despite what people here mostly believe is non-political. They are a pure military alliance. And to which they have one advantage. Which mean they don't care what individual countries do. US can be the world leading economy, that have no concern on NATO as much as North Macedonia because that is a treaty, so NATO would have to treat US the same as as North Macedonia. As such, they weren't limited on membership, again, as long as other NATO member agree.
The world has long been divided into 3 spheres, even as I type you can see the different now, it's North America, Europe and Asia. While Asia has half the people of the world, but still only manage 1/3 of world economy. That's in itself is very alarming, because that's lacking has to be compensated by someone else, and that someone else is what and why the world economy is tilted toward the west right now. Can Asia as a whole pull the entire region out? I don't know, I can't see into the future.
As for whether or not China be next after Russian defeat. Well, I can write a 20 pages essay here for that political position alone, but I will simply say this.
NATO would be coming for China only as long as China themselves wanting them to be.
What China always say is for US to accept the role of China in Asia, the problem is, the reverse is also true. US is in Asia and they aren't leaving either, I mean I don'\t see US packing up and abandoning Japan, South Korea, Singapore, Indian Ocean, Guam and Hawaii anytime soon. And even if they do, this decision is not up to China to decide. Which mean the only way China insist on this to happen is by force. And that would be the reason why NATO is drawn in.