I think that if people are volunteer to make website HTML5 compliant then go for it, but for a good reason specifically.
HTML5 is not going anywhere soon and contains lots of new document semantic tags that would help to make the website accessible to blind people and such.
Everything can be of course kept as-it, just with enhanced semantic structure and better accessibility (and latest version of HTML5).
So yes it is a huge utility for blind people between-other.