The author is overly dramatic about it in order to make a point, to hopefully get people looking for alternatives, so that a good one might take it from pgp in the future (and continues to suggest whatsapp and signal, like, really? That's your replacement for pgp?).
It's not. This is detailed in the piece. What do you think it gets wrong?
That's your replacement for pgp?
One of the key points is that by now we know PGP is a bad idea conceptually. There can't be a replacement for PGP. This is a bit like asking what what's to replace mummification now that we know it doesn't really grant access to the afterlife.