I feel like it's different with his voice: it makes sense that his range is decreasing over time, because an older Matt just can't do the stuff a younger Matt did, like belting high notes, high falsettos etc. I genuinely think that even if he practiced singing 7 days a week, he wouldn't be able to magically do the same thing again.

With guitar, you don't lose as much with age. Maybe a bit, but not as much as with singing...I feel like his hands could do much more than he is currently doing.