Well, if it is true that a lot of owners of "vintage" drums are in their 50's and 60's and if it is also true (as someone stated previously) that as those drummers get older they may either sell their kits or downsize their collections, and if this economy doesn't suddenly and miraculously recover, then it won't have to rain money because there may be a lot more "vintage" sets on the market.
But then the question remains will there be a new generation who is as enamoured with drums from the 50's and 60's as the previous generation?
I know I'm keeping my kits, and may add more in hopes that someday I may have a grandchild who plays, since my daughters have lost interest.
(also because I still play my stuff and it brings me great joy)