If the entire country was geographically lost rather than merely the current government falling, and for reasons most likely completely unrelated to anything you do in play, then yes. I had the same experience playing in Moria in Lord of the Rings Online - we know for a fact that the expedition there that you're so vigorously supporting will in fact fail.
I mean sure, as long as it's just about your characters' livelihood and personal enrichment (and possibly even personal development), as it seems the new Pavis book will focus on, then it's no problem - if by some miracle you're alive in 25 years, you can just relocate. But it does make it less important what happens to the place if it's doomed already (and it's not like you're playing out a tragedy either).
"Yay, we actually restored Genert!"
*blubblubblub*
"Damnit!"
Of course, if it's something that could actually be fought off (which it honestly should be in Glorantha - flooding can be fought by going and beating up the Sea gods, as we all know) rather than a matter of fluid dynamics, and not locked into future history, then we're good once more.