I think. with the increasing power of digital processing to readily perform complex filtering tasks, the switched-capacitor approach has less appeal and practicality.
I believe you are correct.
Performing an unscientific investigation, comparing all of the Digikey’s offerings and then applying the “In Stock” filter, the availability is reduced to a third.
Most of the non-available stock is shown as obsolete, while the remaining is “factory stock” only, meaning very slow moving parts.