I think Andy could beat Nadal on all surfaces except Clay at the moment, provided he's playing his best.
I think Nadal is suffering burn-out a bit at the moment even though he's only played 18 tournies this year, I think last year when he played loads has caught up with him. If he cuts down a bit on the training (and maybe sacrifice a little of his arm muscles) he can be an excellent player for a few more years at least. As it is, I can see him maintaining the intensity for that much longer, i just don't think it's humanly possible.
I think he's right and Andy will get to the top 10 quite soon. Hopefully anyway. I think Andy's aim for next year should be getting into the Masters Cup at the end of the year. Hope he can get a load of points in the first half of the year, and defend the San Jose title.
__________________
To look at a thing is quite different from seeing a thing and one does not see anything until one sees its beauty
Guys who start early don't seem to have long careers. Nadal has been on the main tour since he was 15, he's been going deep in tournaments for a few years now and he's been pounding the weights while he's still been growing. All that comes back to bite you eventually. It's like Hewitt - you get a good couple of years, and then it's downhill. It will happen with Nadal sooner rather than later IMHO.
That's not to say Nadal isn't an incredibly talented player, he clearly is, but I think he put too many miles on the clock early. Watching him vs Blake today and I was surprised at how much better James Blake seemed at points in the match. Blake is obviously one of those guys who can blow anyone off court for an hour when he's on his game, but even so - Nadal just looked out of ideas. I don't know if it's just a blip in form, or if he's just tired after a long season, but I just didn't get the sense that I was watching the second best player on the planet.