I beg to differ. I think the opposite is true: Apart from few exceptions, where collections have true historical value, ordinary coin collections will become less valuable. The reason is a drying up of demand for physical coins:
Once everybody only uses electronic forms of money, nobody will be accustomed to use physical coins and regard them as valuable. In addition there will be no new coin issues, marking the end of an entire collecting field. The probability of new collectors entering the numismatic scene will be greatly reduced as a result. Once the old collectors have died, there will be no new demand for coins.
Apart from that, true collectors don't collect because of a potential increase in value of their collection.
ya.ya.yo!
Ok, Well if this was true... then explain stamp collectors. We hardly use any stamps anymore, since most people use email and social media.
There are still millions of people around the world collecting stamps. So, I beg to differ on your... "beg to differ"
... I think even more
people will get into coin collection, if Bitcoin or Crypto currencies replace Fiat.