A real lisp is more subtle than a fake one, where a person without an impediment just substitutes a “th” for as “s,” but no, SJP does not have a lisp. She has a slightly denasal voice, maybe that’s what the OP is picking up on. Drew Barrymore does have the remnants of one, but it is not as pronounced as it was when she was a child.
Many children go through a “lisp phase,” either when they are missing teeth, or until they have crooked teeth or a bad bite corrected with braces. This is why a natural sounding lisp is hard to fake, because it depends on the shape of a person’s mouth, and the position of their teeth.
Occasionally, children do get a habitual lisp that needs to be corrected with therapy-- there’s a phenomenon by which a person who can’t say something correctly has trouble hearing it correctly as well. My mother is a dialectologist, and so I can tell you this phenomenon is what causes foreign accents. Also, because I was an interpreter in two different public schools, I have had a lot of interaction with speech/language pathologists, so they’ve talked about this sort of thing, and I did take one speech pathology class in college because it was a science credit.
Anyway, what initially happens is that a child lisps because of the shape of his or her mouth, or tooth placement, and then gets accustomed to the sound, and assimilates it, and so continues to produce that sound even after outgrowing the physical problem.
There’s also something called a “lateral lisp,” where the “s” has a “sh” sound instead of a “th” sound. Again, something hard for a non-impaired person to reproduce.
Maybe the OP is confusing a denasal voice with a lisp, but at any rate, lisps are not “taking over.” Even if all those people the OP named really did lisp, I would not take that as evidence that a lisp is becoming the norm.
