It really depends on your product. If you have an e-commerce site, you may find that 5% of your browser base could be IE8. You still want them to spend money.

It really depends on your product. If you have an e-commerce site, you may find that 5% of your browser base could be IE8. You still want them to spend money. It's very much a financial decision. Who is your target market and is it reasonable to assume they will have a modern browser OR you can dictate that they have a modern browser. You then have the issue of accessibility.