im sure they release a new asic one day after the coupons expire.
probably EtHash...
Have you not done research into ETH's discussion on fork to PROG Proof of Work? They already said they will fork.
Source please ?
Go to Ethereum's YouTube channel and listen to conversations the developers have been having recently.
There's no guarantee they will use PROG but they sound very interested. However, they said they WILL fork and continue with POW/POS hybrid.