What to mine after POS

I am currently planning to build a rig capable of 50mh/s for test drive and add more gpus later. Though the future looks bleak as POS will be implemented anytime. I don't know why people are still investing so much in the rigs when mining will be practically dead after POS. Ive searched and not many other coins give out good profits unless you have 200+ mh/s power, DASH/Zcash/M... this leaves us with the options of mining less known coins. Can someone suggest what other coins one can mine? Also, why not mine ETC after ETH POS?

Thanks