The new arrangement with the cittern was only made-up because Mark can't play it properly any more and he knows it. We need to face facts that great songs like this that require power, energy and fast playing are not within his capabilities any more.
Wow, I sure hope you aren't serious, dmg. Any time an artist performs a song for the better part of 30 years, I think that new arrangements are more than welcome to both long-time fans, as well as the artist and his band!
Further I think your assertion that Mark's technical facility on the guitar might be diminishing and that that might somehow factor in to an appreciation of his live performances is completely irrelevant. He is such a master of taste and style that he will always be a treat to listen to.
Admittedly not every artist is capable of this, but Les Paul made some of his finest recordings when he was in his 60s. And I don't feel at all hesitant in saying that I think Mark is doing the same.