Because #bitcoin lies outside of their control, they will have to try to criminalize bitcoin or somehow build roadblocks to ownership. Ultimately, the public has the power to reject it, but most are asleep and if the story is fanciful and convenient enough, they'll buy into whatever is raised as the US currency.

"To this end, the G20 has tasked relevant institutions to improve regulation and supervision of crypto asset—the IMF is contributing to proposals for a comprehensive policy framework—and advance the debate on how central bank digital currencies could impact the global economy and financial system,"

https://www.zerohedge.com/political/g20-announces-plan-impose-digital-currencies-and-ids-worldwide