I know a lot of people are saying your average person buying a computer doesn't know anything about Haswell, Retina etc.
While this is true for PC's, I'm not so sure it's true for Macs. If you are buying a Mac you are already not a typical buyer, as you have chosen a product that is very different (and much more expensive) than a normal PC. Apart from a few people who have more money than sense, most people will read up a bit on what they are getting before they buy. The first few posts/comments/forums they read will mention that Haswell is just round the corner and prompt them to hold off.
It's not like you have to be an IT expert to understand that big improvements are coming. Everyone I know who buys Macs knows what Haswell is and everyone commenting on this post seems to know what it is. We are the people who buy this stuff and I'm willing to bet there are a lot more people like us than you might think.
As for Macs being too much of a switch for most people. I would say OSX is less of a change from Windows 7 than Windows 8 is. That strange metro/modern interface has put a lot of people (who have no interest in a touchscreen PC) off buying a new machine. After trying Win8 I know I won't be upgrading my Windows installation.