As many said you can wait forever to upgrade as the next best thing is just a year away from when you buy.
Let me give the best example, Sandy Bridge CPU released and was huge gains and fantastic over clocker. This was and is a fantastic chip, then after 10 months people said I want to upgrade to a Sandy system, but people said, just wait in a few months Ivy Bridge will be released. So people waited and Ivy was 10% - 15% faster but didn't overclock as well. So those with a Sandy system no need to upgrade, but new buyers could get either and be same performance as Sandy would overclock to match the difference.
Flash forward 10 months, should I buy a Ivy or is Sandy still good enough. Wait, Haswell is being released in a few months. So people waited, and sure enough Haswell is faster then Ivy but again about 10% - 15% faster then Ivy. So end result Haswell is faster but enough to move off an Ivy system? No. Fast enough to upgrade from Sandy? Well if you want the new chipset, but over all, Sandy is still fast enough to run about the same overclocked. You see Haswell doesn't overclock as well as Ivy does. So Sandy Bridge chips are slower but with an overclock are still more then modern gaming needs.
As for Haswell E that will probably be a $1000 chip, and not worth it to most people playing games on a home PC, or doing some work. If your a professional graphic designer for instance using Photoshop (for example), that uses a lot of ram and very well multithreaded it makes sense but not for the average home user and no game company will aim for that chip. Haswell E is not mainstream, and while AMD has a lot of 8 core chips it is actually:
8 real integer "cores"
4 real FP "cores"
so called a 8 core chip. It is a nice chip but Intel are faster per core but cost more.
Graphic cards are another matter, the usual new models are a nice performance bump each year. There in lies the issue, buy now or next year, or the year after or the one after that? The answer at least for me, if my current card is playing games I use on high, I wait till that is no longer the case then upgrade. I won't wait a year, but 3-4 months I will. If a 6 month or greater wait, then odds are good any card out currently will play the game on max, if not then waiting is fine for the new card. Easy answer why if current card you use won't max it, and the newest card won't then you pay a lot but not getting the max performance, so why bother unless the current card won't play it at all.
As for memory new ram is going to be very expensive with little to no visible gain.
TLDR:
So waiting on a cpu upgrade for Haswell E is not worth it. It will be to expensive with about a $1000 (estimated) price tag on the chip itself, and DDR4 will be probably twice the price or more then DDR3 until production raises and prices drop. Just not going to be worth it for the majority of people.
Calebe
