I always thought of Gallifreyan as of Old Greek. We know there is a musical element to the pronunciation because there's accents that indicate tone, but we're not sure how it would have been exactly. But at the same time we still have the texts and we can read them (and some really brainy people can even write them).
I'm a sucker for languages like that. Hm (:

And yes, I can't imagine we've seen the last of the Master yet - at least I hope so!