You know, most people outside these forums actually do hold their phone for the duration of a contract (unless they lose the phone and dont have ins, etc).
So honestly, holding back 2.3 on Evo classic makes no sense. That would be basically saying the Evo 3D is only a marginal upgrade anyway and they need more bullets points on why X consumer needs to upgrade. And also the argument can be made that the true gadgets freaks that would dump their current working phone and pay retail for the next are the types to have been using 2.3 via root+flash.
Most average consumers outside these forums don't really care or obsess about if/when their handset is going to get the next Android update. They are more concerned about whether their device works as it is supposed to. Can they make calls? Does their information sync correctly? Are they getting their email? Can they access the web and other services?
The HTC's and Samsung's of the world make money by selling new hardware, not by pushing out updates to old phones. The EVO had it's time in the spotlight. It received it's OS update to 2.2 along with a handful of smaller updates and fixes. Expecting much beyond that is silly. With few exceptions, few smartphones/pda's have ever received multiple OS updates during the life of the device.
If the EVO gets a GB update, great. If it doesn't, oh well. It's not that big a deal because the EVO is still a great handset.