We actually had full support for older browsers and even tested for them before that.

This was our SaaS-like application, btw, which was closed to the public. Btw, the public website also had a number of modern browsers close to 99%.

Trust me, if we actually needed extra support our sales team would have made us well aware ;)

EDIT: Also, this is sort of a statement. I'd rather let old browsers die. I think it's ok to say "no" to customers sometime. I want the web to evolve, might as well play a part on it, forcing people to upload their browsers, or letting their IT department know their outdated browsers are getting in the way of their productivity.