1080 ti vs 1080

Well that's a bit different. If you can wait the next gen cards are going to drop soon. They should be very capable of 4k ultra gaming. Your parts look pretty decent. If you can wait that would be great. If not, still get the regular 1080 and save the rest for a new GPU once released. You should be able to sell your old card at a bit of a loss.
 

TJ Hooker

Titan
Ambassador
Buying a graphics card capable of 4K now, in anticipation that you might get a 4K monitor in 2-3 years doesn't make sense. If you really don't think you're going to get a new monitor before then, get a good 1080p card now and then upgrade your GPU when you upgrade your monitor. You'll likely spend the same or less money in total and end up with a card that's as good or better than you would if you bought an expensive high end card today.
 
Get a 1070ti, $200 less than a 1080, $500 less than a 1070ti & won't hold back a 1080p 144htz screen at all.

3-4 years down the line that $500 you just saved will probably you a then current gen card actually capable of 4k gaming.

Absolute pointless buying a very expensive top tier card now just in preparation for the future.
You're paying a vast sum extra for performance you don't actually need or will use.