It would be difficult to make it illegal in all jurisdictions in the world, so a 51% attack by a fed up nation state or states working together could shut it down. I am not an expert by any means, but it seems within the realm of possibily.

With a per-unit consumption of 3250 W, that would put the electricity capacity needed to power all those ASICs at ~4.4 GW of power. That limits the possible candidates to pull off such a huge endeavor to powerful nation states who would work in coordination with large energy producers. (Jan 2020)

https://braiins.com/blog/how-much-would-it-cost-to-51-attack...