1. Should people be expected to master the English language?Yes. Even in countries where it isn't the primary mother tongue, everyone in the world who wants to succeed in commerce internationally is learning, or has learned, English. Including in China and India.
At the moment, that's because their primary consumer market - America - speaks English. But once they've learned English, it's much easier for an Indian businessman to talk to a Chinese business woman in English - a language they both already know, than for the Indian guy to learn Mandarin.
And inside India, there is no equivalent to Mandarin - a common language used for adminstration across many other languages and dialects - anyway, except English.
2. Should English the Official Language of America?That's up to you. If you're going to make the decision to use something other than English, you'd better do it while the USA is still the global economic powerhouse. Wait 20 or 30 years until you have some really serious competiton (from mabye a revamped EU, AND China AND India, and maybe Indonesia too), and they're all speaking English to one another, and anyone in America who wants to compete internationally would have to learn it anyway.
Thanks to the British Empire (

) you have a colossal inbuilt advantage - you already speak (a somewhat inferior version of

) English. Why throw that away because the US education system hasn't worked out how to teach it properly?
3. Should the leaders consider getting America to gradually abandon the
English language and use an easier language? Define easy.
Native speakers find whatever language, including the most difficult (and English is a walk in the park compared to Finnish or Basque), a walk in the park to learn.
Languages only become difficult to leanr when you're doing it as a second language, usually only when you're doing it after the age of about 8.
American
may need to get better at teaching English as a foreign language, but that's a different debate.
America may need to get better at teaching. Full stop (or period, if you prefer). Especially at school levels - as we've explored elsewhere, top flight US univerisites are about the best there are, with only the UK's Oxbridge and other senior uni's for competition - but that, too, it another debate.