Here's a few thoughts for you:
Language is just one of the barriers to european commerce. Internet translaters help enormously with language problems, but a 140x190 mattress will never fit a 'four foot six' bed! And even if all the car manufacturers understood english, they would still need to build right-hand drive cars for the UK market!!
Different languages provide a richness. It is no accident that english or german is generally used for technical matters, but french is traditionaly the language of diplomacy and love!
With the expansion of Europe, the number of languages spoken is becoming unmanageable. I think that there will evolve a number of core languages (french, english, etc). So a Lithuanian diplomat will communicate with his polish conterpart in a language which is foreign to both of them.
It is interesting to note the re-emergence of regional languages in recent years. For example, Breton, Welsh, and Scottish. People are learning foreign languages, but keeping their regional identities by teaching their children the local traditional language. This opens them to different cultures, but anchors them firmly in a cultural tradition.
I hope this gives you a few ideas!!
L'anglaise