To start off with a couple of potential biases: I’m a polyglot. I learn languages for fun. While I definitely understand how sharing a native language makes communication easier, I probably will never truly grasp the mindset of a person who is okay with remaining monolingual. There are languages that are more or less of a priority for me, but I would never be able to give up all foreign languages.
Secondly, at this time I would prefer not to comment on what the linguistic situation on Earth will look like in two or three centuries. That would require a lot more research than I’m willing to do for one blog post, and even then predicting the future with a high degree of certainty is usually impossible. The one thing I will say is that we are just about guaranteed to see a major die-off of languages over the course of the next century, and there is little we can do about it other than supporting extant speaker communities and recording as much information about those languages as we can.
This post, and a number of people whom I have spent time with, have argued that in the long run, it would be better if the world had only one language, so that all people could communicate with one another more easily. While I personally am very strongly in favor of preserving linguistic diversity, this post is not here to argue that point, so much as to show that linguistic diversity and ease of communication need not be at odds with one another.
To me, there is an obvious way to allow nearly everyone to communicate without unnecessary difficulty, while preserving the world’s languages: diglossia. For anyone unaware, the term “diglossia” refers to the situation in which two (or sometimes more) languages are used side by side in the same community. Typically, each language is used in a particular, well-defined domain — for instance, German-speaking Swiss use Standard German in written work and in education, as well as when communicating with people from Germany, but speak Swiss German (which is not mutually intelligible with Standard German) just about everywhere else.
The aforementioned diglossic system in use in Switzerland is probably a good model for what an ideal worldwide diglossia might look like, although there would probably be need for a few changes — for instance, every local language would retain their own literature and written language, and schooling would be conducted bilingually through secondary school. Universities would probably end up having a mixture of classes taught in the local language and those taught in the global one, much as modern European universities will occasionally offer classes in English. The result would be that almost everybody would be natively or near-natively bilingual in their local language and the global language, and could communicate with people across the globe without having to sacrifice their native culture.
One issue with multilingualism brought up in the blog post I cite is the existence of people who have little to no ability to learn a foreign language. While I personally am not particularly familiar with the science behind how common this is, or whether learning two languages natively would obviate this issue, it stands to reason that a generally bilingual world would probably have little trouble accommodating such a person. If a child were clearly struggling to acquire both languages even with extra help, they could prioritize the common language in order to ensure their ability to communicate in the larger world, without having to worry that they would then be unable to communicate with their (bilingual) family. And if they chose to prioritize the local language, there would be no shortage of bilingual citizens who could serve as impromptu interpreters and translators as need arose.
At any rate, there is no reason to assume that global communication requires everyone to give up their heritage languages. Multilingual societies have been around for a very long time, and it would serve us well as a global community to emulate their model.