I predict "standard broadcasting" (as the FCC calls it) will persist 
the longest in the United States and my hope is that it will be there 
for decades to come.

Here's some data to support Steve's prediction - some recent estimates for airtime revenue (i.e. not counting digital streaming etc) for the top 15 AM stations in the country.  It's an image file so you'll have to go here to see it:

https://i.imgur.com/AeIae3L.jpeg

There's still plenty of money to be made in AM radio - but not all owners know how to do it.

73, Bob W9RAN