New architectures are always coming out. If you wait til broadwell, then you're left waiting til skylake - if you hold out for skylake, you'll be holding out for what's around the corner. There are two types of people, one's who like to get the new tech when it comes out, those who like to wait for it to become refined. If you want bleeding edge, wait for the broadwell. If you want refined, opt for the haswell refresh (4690k).
Most of the info on broadwell is revolving around the mobile sector and most of the 'new' tech involves much lower power consumption. Great for laptop users, kind of a moot point for desktop users. Keep in mind it's a die shrink and every time a die shrinks it becomes more difficult to overclock as heat levels rise faster due to the density on the smaller die. Before too long overclocking won't be much of an option at all. There goes the performance coolers and everything else unless they completely refigure tech and come up with a new method to overclock. That's why we're already seeing lower peak oc's for i5's and i7's.
Currently the i5's are a little sporadic and oc limits can range from 4.5-4.7ghz. Most struggle to get beyond 1ghz over stock. The more cores the harder it becomes as well. The older wolfdales and yorkfields were 45nm. Sandy bridge were 32nm, Ivy bridge and haswell are 22nm, broadwell is set to drop to 14nm.
For the most part without serious competition from amd, intel isn't forced to compete as hard and since they are top dog in performance for the time being, they have no reason to sell off their cpu's cheap. Most month to month pricing indicates they hold steady unless there's a sale (like right now on the 4690k's, the lowest they've ever been). Some stores are ending their sales and prices have already gone back up. Even with the release of the 4690k refresh, you'd think the 4670k would have dropped in price. Or gone on sale to compete with the newer improved 4690k. It didn't, it held price and became more expensive by comparison.
Unless you need mobile or small form factor performance (fanless, htpc etc), I'd go for the 4690k while it's still a good price if you can. Even with the new architecture that's come out one after another (ivy bridge vs sandy bridge) the performance gains were minute really. I'd expect the same here unless they decide to ditch silicon altogether and desktop skylake is some sort of fiber optic space age tech. Doubtful though.