The decision makers were not concerned about making 300 million analog TVs obsolete a decade ago. Eventually consumers migrated to unregulated streaming TV services.
The transition was painless. Older systems had a long, long sunset period while new ones ramped up.
The migration to streaming or cable systems had nothing to do with old sets becoming obsolete. That migration had to do with having more channels and options than just one's local OTA TV stations. That process has been going on for around four decades: think MTV, CNN, Turner and Superstation WGN. And cable itself has been around since the early 50's as CATV systems.
There is no bandwidth for FMs to simultaneously do analog and digital on separate channels. The current hybrid system works fine.
And nobody has proposed changing FM radio to 100% digital. The industry is more concerned with new media, not going all digital (which has only minor quality gains on FM).
TV was different... we went from a very low res system to much higher resolution and even a different screen proportion. And the change was adopted in some form world-wide. Again, nowhere in the world has pure digital on the existing band been proposed.
Pure digital on a different band has been adopted in Europe, pushed mostly by state owned broadcast groups. It was tried in Canada and died. It was proposed in Brazil and did not pass. Those are two nations where state owned radio is much less dominant and invasive.
But diginets on OTA subchannels have proliferated despite streaming's popularity--in fact Rewind launched today in a crowded marketplace. The same can happen with HD radio subchannels with proper attention, despite smartphone in-car connectivity.
Really the only profitable HD usages are very specialized ones... Farsi in LA is a good example. Otherwise, the main use of HD is to allow operators to license a translator and operate a brand new analog FM covering, depending on height, as much as 100% of a smaller market.