The question is an interesting one, but something for a statistician.
I have raised the idea
on the Forum before, but coins, just like radioactive materials or traces of medicine in an organism, have a half-life cycle. Every whatever period, half of the specimens of a coin will have dissapeared.
But I don't think this is a gradual process. Demonetization of a coin is likely to be a peak destruction moment, and for silver coins, indeed a high silver price may speed up the process.
But for the Juliana guilders, I don't think that we will shortly see supplies of them going down. When the silver guilders were replaced by the nickel ones, many people started hoarding them, and till this day, you can buy them in bulk lots by the hundreds on places like Marktplaats.nl:
https://www.marktplaats.nl/l/postzegels-en-munten/q/gulden+zilver+juliana/