Coin owners (developers) try to achieve the highest possible price for their coin. If Electroneum like Monero, change the algo, There will be very small daily trade volume on all other Cryptonight coins. So, it will be much more coins to sell, then buyers need. Open market, and we will have a big price drop.
Graft developers, want the best for their project for sure, and I believe that they will follow trend of antiASIC algo change, and protect the Graft value.
The number of coins mined per day does not depend on the network hashrate. Introduction of ASICs will just cause those daily-mined coins to be in hands of few people instead of many people like now.