I've not heard any official information about HTML6. All I can find about it are jokes, speculation or misrepresentation. For example html6test.com is just a copy-paste of html5test.com with the term "HTML 5" replaced with "HTML 6"
Even if there was a HTML 6, it would just mean more features become available, which has been happening steadily already. For example WebGL 2 isn't actually part of the HTML spec, and is still a significant new feature which appeared without needing any new HTML 5.1 or HTML 6 spec. We'll keep getting new non-HTML-spec features like that as well. TBH these days browsers just add features individually without worrying about the spec version anyway.