True, but this generation is unlike any other in that the hardware has now surpassed the software. The 5870 already allows all settings maxed out in nearly every game presently out at 24" and below and it's going to be a while before this changes. The only compelling reason, other than bragging rights, to even need something with substantially more performance is going to three screens, and AMD owns that niche. I'm thinking that will grow far faster than some first thought considering the across the boards and sometimes startling enthusiasm from the sites that have reviewed a three screen set-up ... to SEE it in action apparently kindles an irresistable lust to have it kind of thing. That means a shift from upgrading to the holy grail of a 30 inch screen to a three screen set-up (and at substantially less cost to boot) ~ a shift from a focus on a Fermi oriented solution (assuming it has a substantial performance edge) to an AMD-Xfire solution ... at least until Nvidia can come up with a multi-screen solution.
For those already heavily into sli/xfire and who have a 30" screen the logical next step is THREE 30" monitors, after all they are, by definition, already way INTO the absolute best gaming experience/edge possible, and a three screen set-up provides a substantial advantage in head to head gaming, and that leads directly and only to AMD, or for those like Coleen Kelly at TWiT who already run 3 30" monitors, the next step is almost certainly xfired 5870's (now that eyefinity supports xfire) and there simply is no reason to buy a Fermi board. It doesn't GET you anything.
Hate to break it to, but for alot of folks, its all about performance. As I said in a post that got removed, I own and use 2x GTX260s in SLI, the 5870 offers very little as a performance boost to me to upgrade. Fermi on the hand should have the performance at launch to compell an upgrade. "IF" it doesn't then I like many people may wait till games make the purchase justified. Beit 5870 or Fermi.