Mosft of us probably agree that Jon is embarrasing himself vocally. It's been happening for a long time and will likely continue and get worse into the future. One question I have for people who know more about singing than I do is:

Does Jon have anywhere to go? It looks like he is dones as a rock singer, but would his voice hold up singing other types of songs? Crooner songs, for example.

Or, is this simply a voice that is broken across the board?

Yes.

If you want proof, here's as simple of an example as Jon shouting "Are you still with me out there?" during Bad Medicine in Rio 2013:

https://youtu.be/0ooDtMhEI6s?t=5578

And here's him delivering the same phrase 6 - SIX - years later at the same place during the same moment of the same song:

https://youtu.be/WznBpQfyOJQ?t=5740

Speculate all you want, but in my opinion it's clear as a day that Jon isn't healthy. I doubt very strongly that he can last another full-length tour during the rest of his life.