> I only said “good chunk” because there are already more than a few reports pointing to a shift in behavioral patterns around calls

Yes, such reports exist and they are easy to find when you look for them. My point is that you are not balancing these reports with the benefits of the PSTN or considering that people who happily use the PSTN aren't vocal about it. I think you are attributing way too much weight to the information you can find, especially when you are looking for it. You then draw an extreme conclusion that the PSTN is not worth maintaining and support it with this flawed analysis of behavioral change.

You might be right but the way you have substantiated your argument isn't compelling.