If the performance you are getting is not satisfactory with your current CPU then go for it, but if it's ok but you wanna upgrade anyway I would wait for Zen 2 / Ryzen 3 if you can hold out for another year, and tbh you can overclock a 2500k to like 4.2 - 4.3 without even increasing the voltage... ah no that was a 3570k but anyway the 2500k was known to be a excellent overclocker so if you can at all manage to hold off I think Zen 2 / Ryzen 2 will be worth the wait.
As I believe and obviously this part isn't confirmed but I believe they will go for 12 cores, but the more important part is that there will be an IPC increase and a clockspeed increase.
The clockspeed increase can somewhat be inferred from global foundries claims about the 7LP node which is a 40% performance increase, which I would take those claims with a massive gain of salt so lets say 20% clockspeed advantage over Ryzen.
that would mean something like a 4.9Ghz XFR on the replacement for the 1800X and 1600X and a 4.4Ghz all core turbo.
add ontop of that a 10% IPC increase and you are already looking at something like a 32% single threaded performance increase, that is forgetting that you might add 50% more cores onto that which is a 98% multithreaded performance increase.
which it wont add up that way in the vast majority of cases, but like 50% in most highly multi threaded workloads and 28% in most single threaded workloads.
I would wait personally if you can, obviously as said if you can't wait you can't wait, I couldn't deal with a 3570k overclocked to 4.7Ghz because I play EVE Online with 5 clients and like to do other stuff while I am doing that, Ryzen was perfect for that.
But atleast wait for Ryzen 2 it's only like 3 months and a bit away then I would also advise waiting for the die shrink of Vega which is confirmed directly by AMD to be the case, so they can either cut power consumption by 60% which I find hard to believe GF's claims on that probably 40% max and that's just taking it as a power consumption improvement only I think they will take a 10 - 15% power cut and put 10 - 15% into performance, which still isn't that great on power consumption or performance, yay 15% extra performance where it usually performs nearer a 1070 than a 1080 so you are talking most like between the 1080 and 1080Ti and decidedly towards the 1080 rather than the 1080Ti.
although GPU's due to there low clockrates compared to CPU's do usually benfit more from die shrinks than CPU's so maybe they could keep power the same and get the full 40% that would only put them a bit ahead of the 1080Ti pulling 300 odd watts when Nvidia will have launched there next gen architecture so AMD might be a little bit faster than the 1180...
oooo it sucks...