Hi!
Speaking *excellent* English is a lot more work, but I don't see that it would be any more than any other language. (Note that I speak no other languages.)
Yes... but then, you'll end up as in the joke, where "classical theater is when the actors are so english that you cannot understand what they say":) It actually already happens. More and more cases are reported, when non-native en-speakers undertand each other perfectly in english> but need an interpreter to relate to native speakers. AS per myself I love UK english much better (have many more friends living under the rule of H.M. :)
Nah, that's just not bothering because they don't have to.
True, most of my friends do barging in France and\or Holland, and as soon as they started to live abroad they also started to learn that there is much more than english, out there :)
Will they notice? The American Empire will need to fall first. (Starting with the US dollar bubble bursting.)
It's already happening. Not sure that we will not miss the American Empire once it will be gone (there always room for the worse) but I'm pretty sure that I will not die under its rule. Economy talks, and migratory movements are simply impossible to manage. In a couple of generations or so the most read wiki in the US will be ES:wiki. And that's the end of America, at least, in the way we are used to perceive it. Not that Europe faces a different destiny...
In a thousand years or so, there will be people speking of neo-anglians languages... and it will be the start of another fashinating story :) But that's something you and I will not see :)
Bèrto