It’s way too late for Istanbul, but a lot of the discussion here will be relevant down the line.
Yes, they can. There appear to be a small enough number of ASICs on the ETH network that they would fail to establish a viable fork of their own, so switching to ETC would seem to be the smart move. But I’m not in that business, so I don’t really know.
I don’t recall any core devs calling them evil. Unfortunately, the security arguments for ASICs didn’t get presented very well during the progPoW discussions, even by the ASIC manufacturers, but we were aware of them, and I doubt they would have carried the day. We can always reconsider whether discouraging ASICs is best–I suspect that efficiency concerns will force us onto custom hardware, but I don’t when. For the time being we have knowingly entered a war between the ASIC manufacturers, NVIDIA, AMD, and our algorithms.
Except that is not a goal of the core devs. We can’t even finance ourselves.