People will switch from IE when they have to. Firefox, Chrome, and Opera all run well on XP. As for corporate America, they'll wait it out as long as they can too.
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.
I've just been told yesterday that a banking/financial software web product we're supposed to use works only on... firefox! actually the guy who said it to me didnt know if it worked on chrome/safari/opera, but he was 99.9% sure it doesnt work on IE (infact they had to deploy firefox everywhere). I was quite surprised, I think the financial sector is not so open to technological changes (I still remember talkin to a large fund corp no more than 5-6 years ago and they had security policies that said that they cannot use VPN (or FTPS/SFTP) on the internet and they must use CDN or ISDN with callerid verification for transferring operations) but if this vendor is still alive, it means that probably its product is good enough to make people install firefox (let me add that it's a tiny vendor for small financial entities, so you wont deploy this kind of software in large banks, but it's still quite odd for that market).
agreed. They'll only replace those systems when the expense of maintaining them is greater than re-writing. I'm 100% in favor of making it increasingly more painful for companies to hold back progress.
Add in that they may be using these custom apps to handle medical data, or financial data, or something similar that can cost lives or staggering sums of money if a browser upgrade causes even subtle errors... so there's a time-consuming and very costly certification process that must happen even for rewritten software, on top of the cost of development.
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.