Hmm i think i can guarantee with almost certainty that G20 will not place a ban on Crypto.It would make little to no sense .What people often forget is that there are so many developers out there that will go out of work if the G20 were to ban crypto's .It would be like all the countries in the world want innovation to fail, develoeprs to loose there jobs and spiral down into a global recession.No one benefits in this scenario.As for bubble bursting and Trash coins being eliminated i am totally with you but even in that scenario eth would survive.