I sometimes wonder why we care. After all, we aren't out there conserving and shooting matchlocks or even flintlocks in any meaningful way. The abandonment of old stuff is not new. If the new generations want to move on to something else, that is their choice. In the meantime, any of them that want to shoot a double are welcome to try mine.
More par for the course nonsense. Everyone moves on, including new generations, as you, they never did start with best doubles. There is no rule that says a small group of them, as it is now, cannot move on to side by sides of their free choosing.
Except for the dreams of a flip flopping prezhopeful, side by sides, matchlocks or flintlocks are not being gathered for the crusher, there is simply little market for new ones. Classics and antiques will be around and they will be owned by younger generations, let's just try not to teach them that the only good gun, is one that thegov has stomped out the will to possess and appreciate.