Unfortunately, mining with GPUs is already happening and has already made non-ICO investors a lot of money.

Electroneum's founders will need some form of control to cap or discern between those 'cheating' with GPUs, because CPU is the actual mining environment, or find a way to recompensate ICO investors whose funds made the system all possible.

I am hopeful they will figure out a solution, but either way — some pain is ahead for miners or ICO investors, if not both.