I think it will be really hard to create one single language all could and importantly would used by all.
All software today could be written in assembly, but it would mean getting up a website could take 6–12 months and probably cost a few million….
If we ever had a single language all would use, that language would need to do 5 things really well.
And while I have seen languages that can do 2–3 out of 5, I have never seen language that can do all 5.
Have really low system overhead and compile to machine code on any platform.
Have terse easy to learn syntax.
Support all the programming paradigms. Procedural, object oriented & functional.
Have really large ecosystem 3rd party packages and great developer tooling for solving any problem in any industry.
Have highly performant bridge to call directly(no REST/JSON/SOAP/XML mess…) to any language. Even if we decided today to rewrite all software to this new miracle language it would take 10 years to modernize all the legacy stuff so integration needs to be seamless.