TL; DR: Are people still collecting old light grey pieces?
Longer: I've been an on/off into Lego for a while (primarily, off for life reasons). However, most of my pieces are from when I was a kid. And since I loved Castle the most, I have a decent amount of old light grey pieces. My wife and I might have some kids in a few year and I'd like them to have my Legos but I also want them to want them. So part of me had been thinking about selling the old light grey stuff and buying some of the new colors. This is contingent on people actually wanting those pieces though. So before collecting it all up and offloading it, I'm mainly figuring out if people still want it.