One language?? That would make me very sad :( I find every language very beautiful and so interesting. Each language comes with a group of people each with his or her own culture, personality, and history. I don't want any of that to disappear.

It is a possibility, but I don't ever see that happening though. There has been a many languages that has gone extinct but that was due to there not being any one with the desire or anyone left to learn the languages. As long as their is someone present with the desire to learn the language, the language will probably not go extinct. However, I have seen and heard of people who abandon their mother tongue for the other language such as English which saddens me. Don't get me wrong. I love English. Its a language that has so many words to convey how I feel. I also love the accents of those who speak this language. :) Convenience vs culture?  I take the culture part. When has anything worthwhile in life been easy to obtain?

That is not possible. There are so many languages and dialects and even they speak different languages in one country.

I think it is already happening. Not trying to sound ethnocentric but it seems that English is becoming the lingua franca of the world. Perhaps not every single person will ever speak the same language but it will come to a point where one will simply have to speak a common language in order to communicate on a worldwide scale.

i think it is impossible...there are thousands of languages all around the world.this is the culture of human and it has spreaded for thousands of years. It is good that human want to learning, More and more people will know well two or three languages. 

Speak just one language in world is sad and is saying for we forget our sources almost genocidal. I think people will refuse speak another language and forget the native language. So I think that is impossible, and learn languages is a amazing thing, and also to avoid memory problems :)

We have evolved, that will be the opposite