I'm not buying into the language theme. It seems like we will have to suspend disbelief imagining some weapon that obliterates the "lingua franca". The details are missing but it seems like the skeleton of the plot in the trailer hints at something ignorant of linguistics.
At points it's referencing:
The concept of 'language as a virus', an idea that explores the origins and nature of language, was introduced by renowned junkie and counter cultural icon, William S Burroughs. This arguably is the precursor to Dawkins' Meme Complex.
The largely discredited Sapir-Whorf Hypothesis, which suggests the structure of language affects our understanding of the world. This is a key component in Orwell's '1984'.
There appear to be a number of reflections/dopplegangers across TPP and GZ; a favourite subject of classic literature like Stevenson's Jekyll and Hyde and The Double by Dostoyevsky.
There are also allusions to Moby Dick (revenge, huge fucking flaming nuclear whale) and Lord of the Flies (pig's head, Eli, Child Soldiers).
Two of the characters, Codewalker and Quiet, are language themed. The latter of which is deprived of expressing herself via spoken word.
Big Boss himself is deprived of language due to his injuries. He doesn't speak as much and he forgets Russian, requiring translators to assist him during gameplay.
Skullface is a character whose mother tongue is usurped and replaced by a succession of different foreign forces. They take over his home country and force their way of speaking (and thus, the trailer suggests, their worldview) on to the people. Arguably, the Russians in Afghanistan are doing that to the locals too.
It sounds like a pretty big through theme to me.
Plus, I doubt there will be anything as crass as a literal weapon that wipes out words. Kojima is a nutter but he made MGS2, which is thematically perfect in my book. MGS2 didn't use a 'word-gun', it had AI and nanomachines as censors. I think we'll see the birth of that concept with Zero's 'Intelligence Without Borders' concept from GZ. There was, after all, an AI Pod in part of the trailer.