Well you can take my thoughts as far as you an throw them but for me, I look at buying new components this way. If what your gonna buy now will hold you over for the next 2 to 3 years then buy it at the price your willing to pay. Bottom line is, new tech will come out that is usually better and usually costs more but at the same time some of the new tech is way ahead of the games that need that much power anyways so if you wait for the next line of new tech then you will just wait again and again and again because new stuff comes out all the time. I am willing to bet that if you buy a 7970 Ghz now it will last you 2 to 3 years in the games that will be coming out for the next 2 to 3 years and if you need more then you can always pick up another 7970 Ghz and run Xfire and I bet then it will be more than enough in 3 years to run those future titles. But if you wait then you will always wait because we know the tech is growing much faster than the software games to catch up with the technology.
Hookster67 is right, there is always something new and better around the corner in the tech world. The 7970GHZ is the fastest single gpu you can buy right now. If that gpu will meet your needs, I say go for it.
If you do buy a 7970 Ghz edition I have tried 3 different brands and now am very happy with the Sapphire Vapor X 3gb edition. It gave me the highest and stable scores in all my benchmark tests and definitely runs all my games on max settings. I do feel that in maybe a year and half or so I will wait for the price to drop and pick up another one to Xfire them and that should hold me fine. Besides how long do we really know when the next series will come out? Do you want to wait? Again back to my original post. Buy it now if it gives you what you need for the price your willing to pay.
The the awesome thing about buying the Sapphire 7970 Vapor X 3gb Ghz edition card is the 3 free games. Not sure if you like or will play them but I already made use of Sleeping Dogs which went to my son and Hitman will go to my oldest son and I want Far Cry 3 so those are all great bonuses that would cost $150 bucks so its all extra added goodness.