[si1entstill]

Agreed. When I was younger, talking to older (40+ year age gap) people was a bit of a minor shift in vocab or syntax, but I wouldn't call it a "code switch."

If we have hit a point where communicating with people speaking the same language in the same region who are only a generation removed (or 2 at most) requires a "code switch" carrying substantial cognitive overhead... we have a problem.

I'm not claiming that it isn't happening, but it seems like a misstep to just accept it as inevitable. Communication with most of the rest of the same-dialect speaking population of a region should be an innate skill by the time someone is in middle/high school.

(non native speakers or transplants are a whole different ballgame, but I don't think that is what the author is discussing here)