CPU is not like GPU where waiting for a new gen or even new model can mean night and day for the money spent, the growth of CPU power has been slow for the past several generations.
Even if Skylake suddenly doubles in performance compared to Haswell (unlikely to happen, but for the sake of argument), not many games are actually bottlenecked by CPU, hence the improvements you will get going to the hypothetical skylake is still going to be minimal.
I'd say, if you are going to upgrade your CPU, now is as good as any.