Just get 2 1070 if that is your revenue aim
I can't because of my funds. 2 GTX 1070 costs about 1000 dollars while 4 GTX 1050 ti costs 600-650 dollars. I am waiting a bit more before taking the decision as every card is going down in revenue in a day. I am waiting for newer cards to see if they are any good and if they can do for example 50 mhs for a card in ethereum I will get one of those even if the price will be expensive.
Ho wow you are right did not expect the 1070 to be that much now... i got my 1080 ti's for less xd
Anyways from what i have heard Rx Vega is not gone be anywhere close to that (might be wrong ofc)
Those are the only other Gpu's confirmed at this point for this year.
And Volta (20** series of Nvidia) slated for somewhere in early to mid 2018