You can take it from the other end. These employees are locked on IE7/8 because there's not enough external forces to make it a business issue. When they won't be able to use critical resources because of their browser or OS, the upgrade will just happen, how painful and costly it will be (as long as it's less costly than not accessing the said resources)
Actually I agree with this line of thinking. I we could in fact fork IE7, replace it at the system level and people were enthusiastic enough to patch bugs and security holes forever, why not.
