It’s probably safe to assume that George R. R. Martin is following those constant conversations about his work with a close eye, although he doesn’t like to engage in them too much. That’s a normal attitude for creative people, especially writers, and it’s not like he would have much to add to the conversations in the first place.
The best course of action for Martin right now would be to keep quiet about his work, and only talk to his fans once he has something concrete to show them. On the other hand though, he should try to make sure that this doesn’t take too much time, as there’s a limit to how long people are willing to wait for the next book.
At some point, despite the huge initial popularity of “A Song of Ice and Fire”, people are probably going to give up waiting for the next release and will move on to something else.
That would be a disappointing development after such a strong build-up, but it will also serve as a very clear warning to other writers in the future. No matter how much success one might see with their current work, maintaining the status quo is just as important if they don’t want to lose it all. Hopefully that’s not what will happen to Martin though, as the writer doesn’t really deserve that.