IE9 does have compatibility modes for IE7 and IE8 already (somewhere on the official IE blog there's a flow chart describing how IE decides what rendering mode to use for a given page; it's terrifying)
My understanding is that IE's entire user-base consists of update-averse users these days - everybody who can stomach the idea of changing browsers is already using Chrome or Firefox.
My understanding is that IE's entire user-base consists of update-averse users these days - everybody who can stomach the idea of changing browsers is already using Chrome or Firefox.