In the movie Threads (1984) the English language fundamentally changes following catastrophe. Is that linguistic scenario likely?

The movie Threads (1984) is a bleak BBC post-apocalyptic classic that unflinchingly depicts the scientifically grounded (and, in some cases, purely speculative) impacts of nuclear war on the United Kingdom. The entire film is on YouTube and it is brilliant and harrowing.

SPOILERS FOR THREADS FOLLOW

By film's end, a decade or so on from nuclear war, the English language has fundamentally changed, though it's still somewhat recognizable to those familiar with the British dialect.

For example, the standard English statement "Oi! What are you eating? A coney! Give it up!" (made by two rough survivors to a main character cooking some meat) sounds roughly like "Oi! One B (sic)? S'eatin? Coney! Gizza!" (The exchange can be found at 1 hour and 50 minutes in the film online.)

Another example is "Coming! Babby coming!" said by a heavily pregnant character. This is immediately understandable, but it is barked and reflective of heavily degraded vocabulary and syntax.

Older generations still speak standard English, but youths have a sort of rough feral, isolated speech - something that could perhaps be called a degenerative dialect - that reflects deprivation and isolation.

Could you please speculate and share your thoughts on the viability of this linguistic scenario? It strikes me as somewhat incredible that this could all occur within roughly a decade's time, but I'd rather get your informed takes. Thank you!