Above $300, plenty of gear will be profitable post-halving. And if it isn't... it will drop off, but not faster than what is corrected by the adjustment window. As mining gets less profitable, the cheaper way to acquire them becomes the market, which adjusts incentives accordingly.
I hope so. And people say things were OK last halving. But I think I noticed in the data that the block time did lengthen out for a while after it happened. I'll have to run the numbers.
GPU days, pretty sure I ran at a nominal loss for a while there, harvesting heat to compensate. What's old is new again. At least the field was a bit more level back then for the little guys. GPU rigs actually took some maintenance, even if it could be streamlined with scripts and pdu's with ip control.