A few months ago, I threw several brand new Channel Plus modulators away that had been collecting dust for years.
My thoughts were (besides not using any for over a decade), everything is digital and would never need these again.
Any old systems I ran into with them, would be better served by upgrading to HD modulators if that was needed.

As always, as soon as you throw something away, either you or someone else will need it. No matter how long you hold onto it  :)