One of the main ways that the use of OTA spectrum can be made more efficient (which is what the point of all this is) is multicasting, something that is only possible because of the "HD standard" (as you referred to it) that was defined.
I find it ironic that so much effort went into defining the HD standard in terms of OTA transmissions only to see the broadcasters wither away just as things become fully implemented.
It seems unlike that generally stingy, self-centered American taxpayers would spring for "real broadband IP" that is truly "across the nation", at least not in my lifetime. So while broadband deployment might reduce the need for OTA, it won't "end" it.
One thought -- there is a big push to spread real broadband IP across the nation. The final service is supposed to be cheap or free and very inclusive. That might just end the need for OTA.