The way I see it you have today the following language situation worldwide:
people (should) know
the local language, English as the world language and one of the other main communication languages:
French, Russian, Spanish, Chinese, Portuguese, Arabic, Turkish and maybe also Italian, Korean, Dutch or Polish.
I'm in doubt about Indonesian, though I've recently heard that Indonesia has the fourth most dense population in the world, I think that it remains a local language and that English is used by the people doing business over there... (not sure).
Pieter Jansegers
Comments
You didn't mention the role of Esperanto. Is this an oversight? There are even Esperanto speakers in Belgium. Anyway, take a look at www.esperanto.net What do you think?