Which Algorithm will be hit next by ASICs is wrong question, right one would be this: Which algorithm will be hit next by Bitmain? Yeah they will make GPUs fully unusable, there is still Nvidia GPUs which are more profitable on hashes like Lyra2v2 or neoscrypt. Personally I would say next is neoscrypt. Did you remember how profitable does Nvidia GTX 1080ti was for a while this winter? It could ROI in 2 month (in reality this situation was only for 1-2 week) on neoscrypt coins. I highly believe prices will rise and same situation will happen, bitmain will take care of it.
AMD perform better now in lyra2v2. Rx 580 gives 40+ Mh/s. They are many high quality lyra2v2 coins and neoscrypt for some reason is popular with shitcoins.
But I can see there will be revival in GPU only algos. It is an endless cat and mouse game and those projects who gave up will regret.