Thing is, switching the "world language" becomes a more expensive endeavor as more content exists in it, and more speakers understand it. Last time that happened - when French was replaced by English - the numbers were very different. Sure, many educated people spoke French, but nowhere near as many as there are English speakers today, even in proportion to world's population. And it was not nearly as dominant for content: science was mostly done in national languages, and so were books.

Two things changed the landscape a lot. First, universal school education, which in most countries includes at least some rudimentary English, vastly expanded the number of people proficient with it to some extent. And second, the amount of cultural and scientific interchange has skyrocketed, with both effectively standardizing on English as the common language.

So, short of some kind of near-extinction event that would unwind our progress a couple hundred years back, I don't see a high likelihood for change. It seems that we're in the beginning of the "common language" era, and English - or whatever it evolves into over time, anyway - is going to be that language.