I'm okay with newer pages not being viewable by browsers more than 10 years old. Upgrading your browser every half decade or so seems eminently reasonably, if only to ensure you get all of the security patches that are no longer being backported to EOL browsers. Of course, with browsers like chrome, they are auto-updating all the time anyways - so it's not like you have much of a choice.

What is more important to me is that older web sites continue to be browseable (to some degree, bit perfect rendering isn't essential) 20 years from now.