This is a strange question. I know. Why would anyone want to change one's language? It is true that many are interested in studying foreign languages as a second language or such. But few would change one's language.
Imagine. You were born in a very small country and you were taught a very minor language. You grew up without having no question about the language. Then, suddenly you notice that people of other countries use different languages while you have access to virtually anyone one this planet via The Internet. There is still a huge barrier called language. What would you do?
So far, people would learn foreign languages to communicate with people who do not use a common language. The fundamental reason we need a lingua franca is that we don't have a common language globally yet. Why not create one? That would be the best solution.
There seems to be two major hurdles; one is the cost of learning a new language and the other is a strong attachment, which is huge. Language is one of the most powerful conditionings and it is almost our second nature. Very difficult to change. In fact, nobody wants to change one's language unless there is something compelling.
However, if it is worth it, it's better to make it happen even though it is difficult. The better future can be created by design not by chance. Don't you think?