I immediately thought about that after posting, but in reality markup is a clunky and expensive way to dictate this and it would create a lot of waste for something that would be used infrequently.
An interesting idea that comes to mind is the concept of a Mobile Stylesheet / .mss file that would define elements by ID / class and dictate what those elements would represent in a mobile UI. Then you wouldn't have a bunch of needless data-mobile-intent="blah"
That does sound like a good idea, definitely preferable to keep the markup a bit cleaner.
Honestly, I don't know if I care as much for a web-view based product, as Phonegap/Cordova have already been serving that purpose (at least for me), but what you've mentioned, if implemented, would definitely be something I'd use.
An interesting idea that comes to mind is the concept of a Mobile Stylesheet / .mss file that would define elements by ID / class and dictate what those elements would represent in a mobile UI. Then you wouldn't have a bunch of needless data-mobile-intent="blah"