I don't think we'll see a numismatic value increase commensurate with that of a bullion value for common date coins. Rare dates will always be rare and will follow a trend of their own.
A lot of the 90% silver goes into bulk bags, rather than actual melting, and when/if prices come back down we will see plenty of the common dates again priced from a numismatic perspective. Although higher grades will get harder to find due to the bulk handling.
"Common" US gold coins I think will tell a different story in the long run. I've personally seen a lot of late 19th and early 20th century US gold go right to the melt pot. Some I can save depending on who the owner is but there has been so much of it, and the price so high that the amount one person can save from being melted is just a small percentage. Then if you can save coins from being melted you need to find a buyer and many don't want to pay over melt, so the cycle continues.