They (Bitmain) will feel the pain of gambling. It is not very often a coin opposes their invasion of the space, they are not really use to losing. They will probably try again, and again, until the they realize it is cost prohibitive and they can’t force their way into a space they are not welcome. Then they will either move on to the next target, or silently build an ASIC and mine away themselves (which they have done before). I think Monero has the right answer for now, periodically Fork to knock even the silent ones off, make it clear they will not be allowed to force out th. There may come a day where Bitmain isn’t the company to deal with, a day where ASICs have a healthy competition and access is ubiquitous like CPU and GPU, but that day is not today. Until that day comes it is in every coins interest that is not open to ASIC from the start to keep Bitmain in check. Otherwise they will get to watch Bitmain dominate and overtake them whether they like it or not.
Another edit, saw another point you made:
They made Equihash in it’s current configuration ASIC, which was pointed out long ago to be sub-optimal. Change this to be more optimal IE use more memory if necessary if that alone will kill them off, or fork to another algo if that is what is needed. X16R is pretty darn ASIC resistant currently, and apparently energy efficient based on posts I’ve read, both are postives. But my understanding thus far is simply tweaking the algo settings would be enough to effectively brick their existing miner at this point. That’s the immediate goal, make the uninvited guest unwelcome.