2) Most people don't "consume" literature or poetry, and it's unclear to me that non-performance art requires language. (I appreciate Rennaissance painting, but apart from the occasional Latin writing I don't need language to understand it.)
Disclaimer: Besides English, I'm reasonably fluent in Spanish (more so 35 years ago when I last lived in a Spanish speaking country), and used to be reasonably fluent in German, French, Tzeltal and Shuar (and a bit of Italian and written classical Greek). So I have every reason to hope this study is correct. But I have my doubts.
AI won't be able to succinctly translate that joke and have it hit the same way. As an experiment I just fed that into ChatGPT, and it did explain the pun in 6 paragraphs with quotations and a bulleted list, but that kills the simplicity of the humor.
That said, there are plenty of jokes in English. Stop me if you've heard this one...
Where they do, there needs to be a coincidence where words with multiple definitions happen to have the same meanings in both languages, or there happens to be a similar saying in the target language. Often this is not the case. Translators often just make up entirely new material to substitute in for that.
In Latin America, most countries speak Spanish (with the obvious exception of Brazil and smaller colonies from the other European countries), so the every day pressure to learn another language isn't there and English becomes the "obvious" choice. I don't quite get why you seem to discount English entirely.
There's always been a Lingua Franca. It hasn't always been the same one. There will likely always be one.
It will help you communicate, but not partake.
If this happens, professional or reliable translations will only be accessible to those who can afford/pay them, leaving everyone else stuck with the errors produced by LLMs.
To use machine translation, one have to know the language to review the output; otherwise, you're doomed to mistakes. Whatever you do with LLMs, the same thing will happen.
I would name all the marketing surrounding the A"I" as the LLM's blindness virus, or something similar.
That could a long time or it could be a very different implementation than the one you describe. Half of the world knowing 2 or more languages and that has been growing over time. I don’t see the evidence that technology will soon close the gap of speaking and understanding another language when in comes to communicating with family, music, business, participating in community events, volunteering, or even intimacy.
When I move back to Japan I'll wear something like Even Realities glasses, and when unknown vocabulary gets used, display that. Personally I think this will help me learn better than before. But let's wait and see!
I'm very hopeful about learning-acceleration tools. Just think what will be possible with Neuralink.