Suppose this happens - his stated dream of global town square dead - except it was already because most people in the world live neither in Europe nor US. China has wechat behind their great firewall, russophone areas have vkontact and telegram and their alternate reality, meanwhile, in much of the rest of the world I fear Meta dominates (even in francophone Europe, and Africa so I'm told).

So - forcing europeans to rethink could give the fediverse an opportunity - but it also hasn't penetrated much globally, the real challenge is to broaden beyond english speakers and north-atlantic. How to do this? One issue is fediverse is best on desktop, while most people in developing countries are using small screens. But it's not just about tech - there are big japanese fedi-communities with little interaction with the west, presumably due to language barrier.
A decentralised system could even thrive in authoritarian states, if there is some way to protect server admins. I recall twitter seemed to play a key role during the Arab spring, what's the replacement ?