Theres a reason why Bitcoin was called a bubble..
I strongly believe Cryptocurrency will bounce back... but in a different form with a higher hash function than SHA-256 and probably strictly managed by some elements within the G8.
Bitcoin was a test but the world must still go fully digital in basic finance administration and other areas as well
Tulips were called a bubble as well and they never bounced back. Not all things that experience a bubble will one day recover. Even in the dotcom bubble only a handful survived.
Advancements with hashing functions are probably inevitable if bitcoin is to survive and scale but I don't think it will ever be controlled by the g8 or anyone else, people use bitcoin because of its decentralized nature. Without that it's nothing.