Wait and see indeed. 1151 is a bit on shaky ground right now, Intel essentially pulled a "Tualatin stunt" just a few months ago when they announced that you needed new chipsets to use Coffee Lake processors, despite them using the same socket. Even for the 4 core, i3 parts.
There's a supposed 8 core on the way, possibly branded i9 instead of i7. Wait and see what happens with the chipsets/socket at that time and then decide.
RAM is also very expensive at this time, expect to pay an arm and a leg for 32GB DDR4. Is there something you wish to do in particular that the 4790k feels unsatisfactory with?