I am running 5 RX 480 on a windows 7 on a nanopool. A rough calculation is that I make $150 a month from all 5 cards. My investment into it is about $2000 and my ROI is about a year. Are my calculation right??
You will never ROI when ETH goes PoS.
There always has been an altcoin present to mine with GPU. After ethereum, we can mine Krypton, Expanse, Shift, etc. @mewhoyou, in my opinion, you'll eventually ROI, even if ETH doesn't remain PoW.