I don't think pop music leaving the AM band for good is anything to cheer about. Unless you want more religious programming on the AM band, which apparently is not everybody's cup of tea.
Radio Disney wasn't bad to listen to, for what it was. I liked tuning around at night and hearing the odd Disney station's electronic pop music thumping away next to the usual talk, sports, Spanish religious and ranchero programming that covers the band.
The religious organizations seem to be the only ones who have the capital who are willing to bet on AM, so you probably will find a few of the Disney stations going religious. A failing AM station outside my metro area just went Catholic / EWTN. From what I gather, the doors weren't exactly being broken down with other potential buyers.
A lot of the Disney stations are in metros where the 3 main sports networks already are covered, so you probably can rule out sports. As for Mexican music, a lot of the markets where Disney stations are located already have those, including stations on FM.
I read that Disney had 16% listenership on AM, which is pretty high, considering the demographic. But OTA radio is more expensive than streaming. So it was only a matter of time.