I have a few pieces that I wonder about when I drop dead. When I was a kid I bought a 68 Plexi for $425 and that was a lot. This was in the 80's. HAD to have that sound cause thats what was the thing. Today a lot of kids are into modelers cause thats whats in and wouldnt even think about using a vintage Marshall. Not all kids, but when I taught the majority of my students called them dinosaur amps.
It would be interesting in 30 years from now to see if digital has improved to the point that you can get the tone and feel of a vintage amp in an all in one box. Some guys swear they can now. I am completely open to having a nice small 3u rack and get everything my gear does now, but for me its just not happening.
I guess if your using the stuff or dont really need the money then I would hang on to what you can. Its a sellers market for sure and if your pretty positive you will get rid of the stuff at some point, then now would be time while the gettings good.