current generation cards will not be able to handle games that are released two years from now.
Not trying to be an @ss but the 8800GTX was released back in November 2006 and it will play games released in November 2008 & IMHO in November 2009. The ATI 9700pro I think it was played well for at least 2 years back when I had one.
Despite all that you make a very good comment...200 series cards are not worth the price of admission same for the ATI 4800 series. The new Cards are useless unless you play at 1920x1200 with 4x AA & 16x AF & up.