Agreed (in fact, given my anecdotal experiences with polyglots from places like Switzerland or Scandinavia, I wouldn't be at all surprised by the finding that l

Agreed (in fact, given my anecdotal experiences with polyglots from places like Switzerland or Scandinavia, I wouldn't be at all surprised by the finding that learning one language at a young age actually increases facility in other languages). And taking another tack, I think it's important to keep in mind that languages are also vehicles for irreplaceable cultural information that might not be translatable. When we talk about the loss of a language, we're also talking about the loss of conceptual models, epistemologies, turns of phrase, oral traditions, jokes, etc that may be the result of tens of thousands of years of cultural continuity.