One hundred years, a whole century, may seem like a long time but in reality it is a blip of time in the bigger scheme of things and some born recently may be alive then. We see no evidence that things will change so much for the better that by that time the world's nations will agree to a world language.
No, I believe that different languages will continue to flourish. My belief is that many people groups take pride in their history and culture, and will continue to prefer to speak a language that is rooted in that culture. A shared world language would harm the cultural identity of many places and I feel that most countries would not accept this.