I suppose it's possible that some other broadcast entity could put Radio Disney on their FM HD sub-channels, but from reading the article it doesn't sound likely. It sounds like Disney wants to move their product to an internet only platform at the expense of terrestrial radio, and those who can't afford streaming services.
Moving to internet only was actually what they announced back years ago when they took almost all of their broadcast network silent. They justified it by saying that a large majority of the RD listeners weren't using the broadcast stations anyway and listening online. Why they ended up renting the digital channels I don't know. It always seemed like a bad idea to me. FM digital subchannels have a very small audience even when they're being programmed to a mass market. When you have such a tiny percentage of the population as your market who has almost no chance of owning a digital capable radio, why do it?
Many of the newer cars are equipped with HD radios. I think that's what Disney may have been banking on, especially since listeners in vehicles are essentially a captive audience. That's especially true of those who are stuck in gridlock in a major city like LA or Chicago.
I don't think there are going to be all that many kids in the 6-14 year old range who are stuck in gridlock. To and from school or soccer practice I would buy, but that's not going to be much more than a quarter hour.