“The one good thing about British Colonialism is that it gave Indians a common language, in English, in which to communicate. They should thank their lucky stars for British Colonialism for that reason alone.”
Actually that idea has been openly discussed in published discourse in India, and not always, or totally negatively.
The one recognized negative is that English is more prolific among the government & professional elites, and masses working with & for them. The spread of English began in government and higher education because by being common to all involved - in terms of being able to speak it - government and the education elites did not have to master hundreds of languages to communicate well with each other. Mastering English meant each only had to learn one additional language, a one other language its professional peers learned as well. THAT gave English its big start in India.
Also, with all the 100s of languages in India, English is the one “other” language that is not the 1st language of the ETHNIC majorities - such as Hindi (about 40% of India). So, while not someone’s 1st-language, by speaking English they are not deferring to one of the dominant language groups - like Hindi (40% of India). Folks speaking one of the hundreds of smaller languages is going to feel better mastering English instead of Hindi - less of a caste deference since English is not “native” to either one.
It would not surprise me if English becomes the top language in China someday. For similar reasons. Mandarin and Cantonese are not intelligible to each other. Also, there are four primary languages in China Standard Chinese (Mandarin), Yue (Cantonese), Wu (Shanghainese), Minbei (Fuzhou), and between the last three and all the other non-Mandarin speakers there are about 400 million that cannot or do not speak Mandarin. China education ministry even admits that among all who can or do speak Mandarin, 70% of them do not speak it as well as they should. But meanwhile, for business and travel reasons, everyone is learning English.
Here is a list of the nations with some % of English speakers. Just adding them up in Asia and even Africa (Nigeria, the largest African country speaks English), I think English could be on a course where 500 years from now it will be the most common language in the world.
https://en.wikipedia.org/wiki/List_of_countries_by_English-speaking_population
One of the interesting things that is happening in Europe because of the mass influx of refugees, is that they demand the host countries, like Germany and Sweden use English, and not force them to have to learn the host language.