China retaking Taiwan is a possibility. They’re clearly building their military capabilities to be able to hold off the US or make any intervention prohibitive. Taiwan deciding to declare independence will probably be all the spark that is needed.
I can’t see anything happening between Russia/NATO or Iran/Israel. Europe cannot afford war with Russia without the support of the US, and the US can’t afford war with Russia whilst China is looking at Taiwan. Similarly, Israel cannot achieve anything without an enormous amount of American support.
The world is going to go through a phase of recalibration as power shifts from the West towards China. The consequences of this will be countries like Russia reasserting itself. You already see Iran’s unwillingness to rejoin the JCPOA. They know that the US has no more cards to play. They are already a threshold nuclear power and they no longer need sanctions relief since their economy is growing and they’re enjoying greater trade and ties with China.