Not sure what the exact concern is here. So far, virtually all countries on Earth are still represented in DNS. Venezuela, Iran, Somalia, etc etc.

You can also read a lot of anti-Trump articles and comments on countless web-sites, some under .com and some under other top-domains. As lunatic as Trump is, he hasn’t shut that down.

“Is the TLD root management really split up vertically”

AFAIK, yes, it is.

But if the global DNS would somehow break down I guess you either have to find an alternative set of root servers. Or communicate outside of the regular Internet. Such an event surely would shock the global economy.