The difference is that education is now ubiquitous and almost everyone who matters is literate. The reason why Latin diverged into Romance languages is that literacy among the secular class died out, and both the elite and the peasants had no knowledge of formal Latin. (The Church did, but it was relatively weak in Early Middle Ages, certainly not strong enough to push the society to use a certain standard of language.)

Sure, if the educational system today collapses and we revert to pre-industrial state like around 500 AD, English will spontaneously develop into a family of mutually unintelligible languages.

I sincerely hope that this won't happen, though, because 95 per cent of humanity would die. We cannot feed 8 billion people with pre-modern technology.

Romans didn't have TVs, and couldn't still listen to recordings of people talking from a century before.

edit: If we're not killed by corruption, the assumption is that people will be enjoying films made in the 1920's and 30's in the 2220's and the 2230's. That's completely unprecedented, and has to pin a language to a certain extent.

Imagine if during the Great Vowel Shift, everybody could listen (and did listen, for entertainment) to people speaking at length from before. It would have ended up a fashion where maybe a couple of features stuck.

In 2230, there will be 300 years of film to watch. The past will overwhelm the present.

There will be more YouTube and TikTok video generated in a year than the previous 300 - 5 most recent years of film/video. 90%+ of youth video consumption will be contemporaneous to the viewer.