there's nothing left showcasing what he can do.
This is where I think you have it wrong. Yes, there's little left showcasing what he used to be able to do (used to could ), but he does what he can as a 69 year old man. And I think that's fully acceptable. Mark is more than flashy guitar wizardry, even if that's what caught the attention of a lot of us in the first place. It's been downhill guitarwise for a few years now, so to expect him to suddenly be restored to former glory is unrealistic.
I agree, hunter. I would love MK to play all of the songs I love and go out with a bang, but it's obvious to me that he tires very easily, especially towards the end of the show, so hearing that beautiful rendition of BIA, even though it wasn't perfect, made it even more special and moving for me.
We don't actually know what is wrong with MK healthwise, but it doesn't seem to be just an age problem, although it is one of the reasons. Only time will tell.