Your crazy imo haha
1070's ? dude your like a YEAR too late to build a farm with those lol, you are gonna be lucky to ROI probably before they start bring in like 1$ a day each

Plus all that wasted space, did you not consider DENSITY LONG TERM?
New mining specific cards are coming out that are gonna DUST your whole farm if you have 1070's, did you consider THAT?
Im just getting RID of my old 1070 for POWERFUL cards, 1080, 1080ti, and stacking my coins for the new mining specific card + volta and vega
Like you literally picked the worse time to choose 1070, o and in 2 months or less they will be 1/2 price
This is ridiculous in regards to them bringing in 1 dollar a day each when a rig of 6 1070's is bringing in 50 dollars a day or so right now. I like the 1080TI's as well and I was contemplating going with 2 1080TI's and 4 1070's per rig but as of now I am not planning for that. These cards ROI in 75 days right now so even if in 6 months these mythical cards come out and come out at a good price point I probably won't care that much. I really don't like the idea of mining specific cards for their lack of resale value... How is that any different than an ASIC? Once the new tech comes out those cards would become worthless. If anything 1070's will still hold some resale value as time goes on. I guess I like building rigs with one PSU and 6 GPU's but the 1080TI requires an 8 pin and a 6 pin so that makes things difficult. At any rate, I think that Nvidia, depending on your needs, can be much better than the AMD cards and they are also a lot less hassle in the long run.
EDIT: We will also see about ETH going POS but as far as I know there isn't anything formal in the timeline of things to be done but I do know that it is in in the timeline for ETC for 2018. At any rate, 1070's are far better than any AMD card in almost every algo with an exception to Ethash. In reality, even if it takes a step towards POS it will likely be POSW so that it is a gradual process.