Well, maybe. But people still speak Mayan today and they've retained the legends and stories which are depicted on the iconography and actually written in the script, that's how we were able to decipher and read it.
I don't mean to sound like a cultural darwinist, but Athens and the library of Alexandria were razed to the ground and yet we still have Plato today because everybody who got their hands on his writings decided to read, translate, and disseminate it--there was no reason for the Romans to preserve his philosophy, no reason for the Arabian and Persian peoples either, and yet here we are today with complete versions of these texts translated into myriad languages over thousands of years, whereas other cultural properties, perhaps even from civilizations far larger, have simply disappeared, like the Egyptian materials for over a thousand years.
I don't think its wise to be too excited about these potential discoveries, because the reason why these cities can even be recognized and named as such by peoples (namely, us) living and analyzing them hundreds or thousands of years later is because of certain shared psychological and therefore social contexts. They may manifest in different forms, but the parallel developments of civilization across time, in different places, in completely separate contexts, is only on account of the shared, basic psychology of all humans, and in the end there will never be a remarkable difference between the kinds of texts produced by a predominantly agrarian society in the Ancient near-east, like the Egyptians, and a predominantly agrarian society in Mesoamerica.
In any kind of scientific endeavour it is never a good idea to be over-confident, nevertheless I think I have to claim that at this point in time anthropologists have developed a pretty good map of how human civilizations develop, from the totemic cults of tribal cultures to the cosmopolitan sprawls of modern urban centers: no matter where you look or what you examine, material cultures appear to progress in a basically similar manner. And, as I said above, there is no sense in trying to "recover" a lost culture, Mayan or otherwise; those cultures are still alive and well today--cultures never die, they just change, all we can do is create a map of those changes, we can never actually go back and fully understand how a people lived and experienced the world and how they expressed that experience in literature and philosophy, since our interpretation of that data will always be tainted by modern experience. But the map, and the contact with the Other, in the form of a "lost" culture, can show us that our modern experience is not the end all be all of the world, there will always be something in these cultures that escapes modern understanding, and I think that in that encounter something fruitful can be born, and therein lies the value of these sorts of investigations.