However, if forced, technology departments are quite capable of installing Chrome or Firefox. I don't feel sorry for corporations who have IE[6-8] only apps. I was there 10 years ago when people said that it only had to run in IE, when I said we should test in Firefox too.
And certification would need to happen again before any subsequent browser upgrades.
So I hate supporting IE6, but I'm working in health care, so I'm pretty sure that I'm going to be supporting IE6 for a while yet.