Yeah I saw your point, but you have to remember that the extra performance of the 1080 is worthwhile if you intend to keep the build for a long time because that extra performance will make a difference in a few years' time. But if you intend to change components quite regularly then the 1070 will be fine.I know, I know, It all comes down to how much I want to spend, But I don't want to pay 2x as much for 10% gain in gaming performance...
I still think you'd be better off with an i5 and a 1080 than an i7 and a 1070 if all you're interested in is gaming? Is gaming your main priority?
16GB RAM is fine, that's what to aim for now if you have the money.
@Punk I think $1mn is perfectly reasonable!