Some extra considerations

:
- English arguably, is or was the language used by the powerful. I.e. It gained worldwide status largely due to British rule in the 16th century (check dates please :p) and later America by later eras.
- English was also simply at the right place at the right time. For instance, had factors such as the printing press been designed prominently for other languages such as French, it may very well have been the world language we see today.
These have played significant roles in the way English has developed and continue to develop, in my opinion

. Knowing this, you might also look at how China's growth as the globe's super power may pose as a threat to the widespread use of English.
You might want to look at how English is the popular choice for advertising, entertainment (hollywood/media/music) and as you say, travel, business and trade, and how it ties in with how English has developed, and will... Where the likes of Standard English can provide mutual clarity, other non-standards begin to indulge in the contemporary cultures and trends of society.
Hope nothing here is wrong, but just some quick ideas that came to mind.
