Just do one thing: let subcontinental indian english do this century to en-us what en-us did to en-gb last century. If the yanks yammer, we can simply ask them to kindly adjust :-)

(Over on this continent, we've also seen the emergence of en-eu as a contact language, much to the dismay of the ethnic english.)

Edit: (clarification here due to rate-limit)

Demographically, I expect en-in to become the english "standard" (just going by history: some english are still salty that most people who learn english these days learn what they'd consider "american").

       pop(M)
    IN 1'300 
    US   300
    UK    70

(Once upon a time, a smiley indicated attached advocacy was not in earnest.)

Edit2: retox — one reason to "save" languages which applies even if no one intends to use them in dialogue is to have a wide variety of empirical examples of language formation, which can then quantitatively inform our attempts to reverse engineer current languages and dialects.

Edit3: as to the argument by economic power, maybe it's just chutzpah, but I'll point out that many dope additions to en-us have come from AAVE, which is not normally considered a dialect representing economic power. As I expect future english usage to be driven by phone chatters, that demographic should correlate with population.

https://en.wikipedia.org/wiki/African-American_Vernacular_En...