But you're gonna need then an CPU upgrade, atleast i7 4790 or any i7,
How many gigabytes of ram do you have?
Which monitor do you have and do you plan to buy new monitor with higher resolution?
Which PSU do you have currently?
Add another same 8GB and an i7 for 4k 60FPS as some posts on linustechtips have similar setup with 1070.
But crucial thing is Which powersupply do you have?
https://linustechtips.com/main/topic/705441-can-a-gtx-1070-and-4790k-handle-4k/
Not max but high.