Honestly, I'd probably just roll with the 4790k for a while. You can overclock that past 4.5 relatively safely. As long as you're just running one card you'll get great performance still. Plus, the new "enthusiast" (which I'm assuming you are, given you have a 4790K) CPU are terribly expensive. I'm gonna have to pay $1000 just for my CPU alone, just to get 40 lanes...
I might not upgrade this generation, cuz the next will be cheaper and who the fukk really needs 10 cores? Like really....
Edit: I forgot to talk about the RAM. Yeah you're good. There's only a very small difference with faster ram. I have faster ram in my latest pc, compared to my old one, but I can't really see any difference.