I doubt anything of that sort will happen! China has already come down heavily on bitcoin and I am sure Chinese elites will not take such risk unless and until they want to flee out from the country. Even if some elites decide to use cryptos to safeguard their wealth (which is highly unlikely) they will use a portfolio of cryptos.
They use OTC exchanges which are still perfectly legal there, meaning there is negligible risk outside Bitcoin tanking. Given the nature of OTC trading, it's not going to impact prices directly, but could have trickle effects of some sort.
I don't think there will be trade wars, what's been happening around is the fear on China getting completely cashless in few years time.
It's literally starting now though, with the US and China raising tariffs on each other's products. This has nothing to do with being cashless.