So the first 15Mbit channel is on the 40Mbit sd channel band meaning that instead of 220 channels you have 150 channels 50 red button and 100 educational channels.
The other 15mb slice is on one of the HD 40Mbit bands bringing the hd channel number to 78 from 108
These 2 channels are shared red button holographic streams. When you consider there are no copy channels or plus one channels across the channel use people are getting better value for money compared with today.
You may get modern movies documentaries or shows on these 2 highly sought after holographic streams.
This is about the limit of sensible UHF and VHF use for the public you may one day be able to do small credit transactions and write small text responses over terrestrial one day with no internet.