You know, I could totally agree with this statement if it weren't for the issues we ran in to with Ivy Bridge. It's no secret now that Intel cheaped out on the heat spreader application by using TIM instead of flux-less solder, but will Haswell and Broadwell have the same application and problem associated with it as Ivy does? Furthermore, 22nm brought about a problem that the solution to has yet to be found, the die surface area. It has gotten to the point now that it is so small that we cannot transfer enough heat fast enough to the heat-spreader to get rid of the heat at a given thermal load. What this means is that further down the road, the "wall" overclocking presents will hit even harder as a chip will reach the point where temps will absolutely take off (see how poor Ivy handles this). I'm trying to imagine how the 14nm die shrink will behave, some pretty innovative ideas are going to have to flow out of the engineering department to overcome this obstacle. So, 4.8ghz easy, I'm not betting on it if it's the progression of the 2500k ->3570k -> xxxxK series and they are constructed like Ivy is. As it is now, anything past 4.5 ghz for a 3570k can be difficult to acheive.
If trying to buy in the next 6 months, just pick the best deal you can period. We are already at a point where most processors just aren't taxed to their fullest unless a very high-end multi-GPU setup is used. Haswell is shaping up to be more power efficiency and a good boost to the IGPU, that's about it though - some even are questioning if it's a "tick" or a "tock" by the sound of it. By waiting, you're probably not gaining a whole lot here by doing so.
DDR 4 is still a ways off, at least a year last I heard. Don't expect this stuff to be cheap at launch by any means either.