Learning one common language (say Esperanto) doesn't mean you'll lose the motherlanguage. Welsh nearly died out 30 years ago, because everyone began to speak English. Now Welsh is back as the motherlanguage (and they still speak English too).
Actually, it does. I'm sure that, if nobody took upon themselves the task to champion the rediscovery of Welsh language, it would have eventually died out. I see it enough here. It's alarming how fast certain dialects disappear. Generally that is the consequence of having to do everything in another language. If everyone here had to do all official communication in English, unofficial would soon follow and the language would slowly but surely, die.
At this point, I think we're not doing enough to preserve our cultural diversity, and while I applaud those who would simplify communication, I must also insist that we not forget who we are and where we come from. Perhaps there is a middle ground, where the mother tongue could be combined with a universal language, but that would probably mean an autonomy of lingual entities instead of the current nations, which is rather impossible at this time. It's so strange that there are three languages in Belgium. adding a universal tongue which everyone is required to know, on top of that, is just silly talk. So you would first have to divide those lingual subnations - which is proving to be far more difficult than suspected.
