One template that I know is used a lot of my sites is the maintenance-page.tpl.php, to keep everything clean on that page too. Can we add a base one here that is more HTML5-magical?
I have a test one here, although I haven't tested it fully. I know there are also some oddities with the preprocessors (partially fixed here) but I would like to test it more before fully putting it in here. But before I walk down that lovely rabbit hole, I rather make sure this is something that you agree should be in here.