I'd say that not supporting browsers below IE8 (or even IE8 itself) is reasonable for many projects. I just looked at the stats for a few of our sites and total

I'd say that not supporting browsers below IE8 (or even IE8 itself) is reasonable for many projects. I just looked at the stats for a few of our sites and total IE browser share is around 4–7% on them. If you have a similar situation on your site/application, I think it's perfectly reasonable not to support anything other than modern browsers, but you have to look at your own stats.