Of the countries where the servers are located, the U.S. has the most extreme copyright laws, which means, sadly, FedGov is the leading candidate to be behind any possible seizure.
It would be interesting if an enterprising journalist were to ask MIT, SF-based Applied Operations, and RiseUp if they've been contacted by law enforcement on this matter. Those organizations host some of the U.S.-based servers. RiseUp has a warrant canary but it hasn't been updated recently: https://help.riseup.net/en/canary
Of course we don't know what actually is going on and it all may be (I hope!) a false alarm.
PS: If multiple governments cooperate and a majority of servers are taken down, what happens to Tor after the consensus interval expires? I don't know; maybe someone more familiar with Tor does. The consensus interval was changed to 72 hours a few years ago: https://trac.torproject.org/projects/tor/ticket/7986
PPS: Remember that FedGov's "copyright infringing" domain name seizures have on occasion taken down non-infringing sites in error, as I wrote about here: http://www.cnet.com/news/dhs-abruptly-abandons-copyright-sei...