The problem i have with yearly updates if this is where they are going (Apple seems to do that now anymore), is once a new release comes out - the tech forums, news sites, hack sites (Tweaks), etc...all focus 100% on the new fangled version and leave out the other versions in the dark, as if the old version is dead. I wouldn't say that this is the case here just yet with Win8 since it has a very lukewarm reception amongst users. I personally didn't like it until I gave it a chance and played with it for a night. Now, I actually find it pretty well built and the Start Screen (Metro screen), I do use, but not as much as most. I spend most of my time in the desktop and use the Start Screen mostly for launching items.
One of the reasons IMHO that IT has stuck so long with XP is because Microsoft still has supported it with security updates. That - and software vendors refuse to build new software to support Win 7. Some IT departments restrict compatibility options because of said vendors software crashing with compatibility enabled. Sadly, with this software, throughout the 11 years that XP has been in full deployment (RTM and beyond), businesses have built themselves on such software so leaving their foundation to go to new software is not an easy option.