The vast majority of English speakers do not live in the US or the UK. English is the most widely spoken language in the world. If you are at dinner with people from several countries, the "Lingua Franca" will almost certainly be English.
The popularity of Mandarin relies on the sheer mass of native speakers in China. That population is shrinking and that shrinking is expected to accelerate. The cultural export of China is inherently limited by its ideology - there's a reason we have (had, really) "Hong Kong Cinema" not "Peking Cinema".
All Japanese people learn English at school; few learn Chinese as you can verify by reading about the Japanese school system from various sources including Wikipedia.
Similarly in China, English is the only mandatory foreign language taught at school.
Frequently, Chinese or Japanese. For example companies in these countries employ translators. Are you suggesting they rely on primary school-level English to negotiate?
You claimed, without a source other than wikipedia, that everyone in Japan learns English in school. I see this [0] on wikipedia which says "a select number of public primary schools ... have mandatory English classes"
