This isn't a temporary speeedbump, it's a permanent end to proof of work mining as an investable activity (and viable sybil resistance mechanism for bitcoin).
If the attacker attempts to keep up the game of cat-and-mouse long enough they will eventually go bankrupt and will no longer be able to participate.
And this theoretical discussion completely dismisses the fact that it's nearly impossible to execute an attack like this at this stage in the game anyway.