As far as I see it, “Brexit” will cause a seismic shift in how we communicate with Europe. French and German are almost as widely spoken in Europe. The question is, for how long will British English remain number one in the EU institutions? And how is Brexit going to affect English language teaching and learning?
It's obvious people will continue to study English for many different reasons: Almost 2 billion people around the world speak English; British pop music spread English worldwide and faster than any other source. Even multinational companies like Samsung have adopted English as a language to improve communication for their business endeavours.
American culture has played a significant role in spreading the English language too, and many students want to be able to watch films and TV shows in American English.
My first guess is that American English will eventually be the leading variety of English, and that the English spoken in Europe as "lingua-franca" will continue evolving on its own, creating sort of a "Euro-English".
On the other hand, Ireland will become the only English native-speaking member state, which could make Ireland a more attractive location for foreign students, – something which will affect positively the Irish economy. Without the support of a grant from the Erasmus programmes, EU school and university students will no longer be able to afford a cultural exchange year in Great Britain, so I assume they will try to go to Ireland instead.
Should we all start studying French or German now?