Maybe he has lost his mojo. If he had any motivation at all I'm sure it would've been done and dusted by now.
I don't think that's necessarily true (although it could be, of course). More likely, he just won't be rushed anymore. And why would he? He's got nothing to prove, and he's written and played more great songs than almost anybody else on the planet. It's great that he's still creating, but it's not that we urgently need 10 or 20 new songs from him. Jimi Hendrix died at 27, and no one complains day-in, day-out that he's no longer delievering anything new. We just enjoy what we have, and in the case of Mark, that's a lot.
The one wish I have for the new album is that it will be on a level with all the previous ones. If he needs more time to make sure that it is, that's more than fine by me.