“The present author can vouch for both the necessity and sufficiency of French as a medium of communication among students from Barcelona to Istanbul as recently as the year 1970.” But:
“Within thirty years all that had changed. By the year 2000, French had ceased to be a reliable medium of international communication even among elites. Only in the UK, Ireland and Romania was it the recommended choice for schoolchildren embarking on a first foreign language – everyone else learned English.”
I wonder how long this dominance will last if London loses its perch as the financial gateway to Europe, a possibility if the United Kingdom really quits the European Union. It’s not like I’m expecting everyone to start learning French or German again. On the other hand, if the French-to-English transition can happen in just three decades, so can something else starting now (or close to now), I guess.