Yes, I'm not sure what the future holds for HTML but I'm confident the ultimate goal of webassembly is to make the browser a secure place to run full native like apps. That suggests some apps will not use HTML and just render everything themselves

There's some incentive to use HTML as it's indexable but it doesn't seem to be affecting mobile, although maybe mobile is in large part successful because of the web? Like the fact that you can post a tweet or a facebook post or a youtube video everywhere. Not sure that HTML is required for that and if it's not then it seems at least possible HTML will die.