Considering that ethereum is mined by 75% of video cards, although I think more, then after the end of ethereum mining, the profit will be low on all algorithms and any purchase price now will seem very high to you. There will be testnet results in June, and for example, I don't want to take risks over several months of mining.
I 100% agree. Actually, 96% of the market cap of GPU mineable coins currently comes from ETH. That could be as much as a 96% collapse in total mining revenue available (although this doesn't consider differences in block rewards). The folks buying video cards at inflated prices today will be the bag holders, if ETH 2.0 goes according to schedule. Of course, if the merge gets delayed by 3 months, they'll probably break even.
The miners who will make profit are those who wait for the crash, buy mining equipment at 50% below MSRP, mine while difficulty is low for a few months, then sell when difficulty recovers. They also have to have a decent power cost (< 10¢/kWh) and need to know the tax incentives available.
Personally, I can't wait for the PoS merge. Right now I'm buying different models of video cards to test them on different algos and learn. When GPU prices crash, I will buy hundreds of cards and pay 5-6¢/kWh (after tax) for power.