45-55fps I would say on low-medium 1080p.
I have a i5 4460 and a GTX 970 on high settings, my CPU goes to 90-100% usage which is bad (my i5 is a very very powerful one, one of the best) and GPU about 60% while vysnced. I get 55-60fps but I stutter due to the CPU, its not my CPU's fault. The games badly optimized, its Ubisoft.
So you'll need the best i5 possible or an i7 with a next generation card.