On 4-5 Aug there will be an eth fork, which will burn gas fees instead going to the miners. How much it will affect mining profitability can't be predicted. May be 40%, may be more. And POS is scheduled for December this year. The remaining POW coins can't handle even 1% of the eth hash power, so the profit will be only for those having very cheap or free electricity. The big mining farms are preparing to shut down and soon there will be a flood of millions cheap gpu's. The prices are already falling, and I guess around December the gpus will be > 10x cheaper. Not a good time to start building rigs, I guess. Still, I see quite a few newbies doing so, apparently not having a clue what will happen soon.