Most of the wealth you listed here is denominated in US dollars, and there's the rub. Unless an extremely friendly to them regime takes permanent power in America (Trump?) they will have to deal with the Fed and Treasury to retain their wealth. Putin found this out just a short time ago.

The US dollar is only good in the US and for purchasing products from those willing to accept the greenback. With a fiat currency and some legislators that understand sovereign money (not the BS propaganda they dole out to the people) anyone who threatens the supremacy of the dollar will find themselves with sanctions and overwhelming exit taxation to strip it away from them.