I'd still prefer English to be the lingua franca for two reasons: plenty of exposure opportunities because it's everywhere; non-gendered so you don't have to play mind games about whether a book is m, f, or neutral

English has an uncomfortable imperial and colonial connotation in many cultures, making it probably not the best choice, globally.

As long as it's not French, I can understand

Be that English, Spanish, or Mandarin.

I tend to agree. But there's a lot of cultural identity and works connected to languages. I guess the best way would be for everybody in the world to just learn "that one language" as their first foreign language.

can't imagine how much of cultural interaction and otherwise productive hours are lost to learning languages.

Tabarnak. I speak enough Quebecois to get myself into trouble.