Dude is ooooooold, not in great physical condition and taking roughly 2,743 years to finish the next book in the series. I'm guessing he's going to croak before he finishes and leave his fans hanging.
I remember meeting Robert Jordan at a book signing back in 2005 not long after he'd been diagnosed with [insert obscure, fatal disease here] and thinking he wasn't going to make the trip. I was of course sad but at least for him he had always been clear about his thousands of pages of notes and hours upon hours of audio notes etc he had been stockpiling so I figured someone would finish. Now we've got Brandon Sanderson writing the last 3 books and so far they are fantastic.
I'm thinking Mr. Martin is not so meticulous with his note taking judging by his blog entries of the million things he's doing that are not in any way related to the series his fans are so ravenous for.
I hope he makes the trip in general because hey, he seems like a pretty good dude. Selfishly though I'm going to be pretty angry at that old SOB if he croaks before he finishes. This is exactly how I felt about Stephen King when he went off and got himself run over before finishing the Dark Tower. He pulled through though fortunately.
I think it's time we take charge and start locking these authors up in bubbles inside of cells and putting them on a strict regimen of diet and exercise to ensure they survive to finish their opuses.