Do you think that English will continue to be one of the main "lingua francas" of the world?
Why or why not?

Explanation:Originally Answered: Is it possible that one day English is no longer the world's lingua franca?

Yes. All you need is economic decline and US losing its economic and violence hegemony. Within EU, it is already happening.

With Brexit, English will cease being one of the official languages in EU. Either German or French will replace it as the hegemonic language, and I speak both. The only Anglophone nation in EU remaining will be Ireland, whose population basis and economical significance are not remarkable enough to heave it as the official language.

China has already eclipsed US as the dominant economy in the world, India is a rising might, and the Schweitzer of the world economy is shifting gradually to the other side of the Pacific. NATO has proved more or less a paper tiger (with nuclear teeth, of course) and US is becoming more and more isolationist all the time.

Brexit is basically UK shooting its own leg. With Brexit, UK will lose all the benefits of the internal markets of EU, the cultural community within Europe and the cultural and linguistic domination and preference within EU. It effectively will become the 51st state of US.

Perhaps the greatest variable in this thing is the incompatibility of US weights and measures with the rest of the world. The rest of the world is Metric, while US clings to their age-old foot-pound units which should have been ditched already centuries ago. They create an immense impediment on world trade, and animosity towards US. This can be a trigger on English also losing its status as lingua franca.

i believe this is