IIRC the lower VHF bands were reprovisioned for the new HD channels, which could fit more subchannels in the same frequency range because digital doesn't bleed into neighboring channels like analog. The higher UHF bands were resold to become cellular network bands.

You are correct it's still there to some degree but I still would be shocked to discover it had more than fraction of the penetration of cable and satellite. I would check but I frankly don't know what industry group would even publish such statistics.