It is unclear when/if there will be desktop Broadwell parts. Broadwell has been delayed, and now Skylake is expected to debut in 2nd half of 2015. There is a good chance that Broadwell for desktop will be skipped, and it would only offer an approximately 5% increase in performance over Haswell, as its main push has been for power efficiency for mobility more than increasing performance.
If you can wait for Fall of 2015, I think that Skylake will be worth the wait, but for the reasons above, I would not hold out for Broadwell desktop. If you need the desktop now, the 4790K is a great chip for the time being.
http://arstechnica.com/gadgets/2015/01/quad-core-and-desktop-broadwell-chips-still-mia-expected-mid-2015/