Once ETH goes PoS only mining rigs with free electricity will be able to mine. The rest will have to shut down. That's probably 95% of all the people mining around the world ETH and the rest of coins.
Why would you care about this GPUS?? Why would anyone care about mining on any gpu in the upcoming years?? You will not be able to mine with profit. Probably never again.
I don´t think so. In the BTC was mined with GPU´s, and after ASIC´s arrived the field, GPU mining not died, same think is happen after the first LTC asics are going live. And the same will happen after ETH is going to POS - sure maybe in 3 or 4 years - vitalik must test his POS first on DOGE XD
Sure we have much more hashrate as in the past, but we have also much more coins to mine. Some people are going out, but this happens every bear market. So i don´t understand the fear and why all people only looking on ETH.