I have no progeny to pass my bikes to, either for their sentimental association evoking thoughts of dearly departed old Me, or as a modest financial legacy (and I do hope there will continue to be a gradually rising future value placed on the bikes themselves).
But, thoughts of my mortality have certainly crossed my mind. As others have mentioned, there is always the possibility of liquidation via eBay. However, I'm always hoping that some of the interest in old bikes which I may have helped to set the seed for in younger local cycling enthusiasts, will someday mature.
I can think of nothing better than to pass on a cherished bike to someone I know personally, who I could be convinced would care for the bike... and of course, continue to ride it, as well.
I agree with Chris, that there is nothing wrong with gentle upgrades to an old steed. Currently, my greatest concern is (and it really should be) happily riding my bikes, and if a set of cheap but expedient SPD pedals or a supremely smooth shifting modern derailleur and teflon lined cable housings on a 40 year old bike makes the difference, I can now live with this. The core of the original bike including either original or faithfully restored enamel and decals will remain intact for a future faithful restoration, perhaps at the hands of a future owner.
To be honest, I have noticed that some of my absolutely "correct" bikes now spend increasingly greater lengths of time in the stable (i.e.: on the wall). This is truly a shame. But, with limited riding time, and an abundance of bikes to choose from, I think many others among us may recognize this same phenomena.
For some of my bikes which I've now refitted (or defiled) into very comfy riders, I have actually boxed up and labelled all the proper vintage components which I'd (temporarily?) removed. However, even this is not really necessary. After all, I'm a cyclist, a rider, and not a museum curator (as I have to keep reminding myself).
And, the quest for restoration parts and the education which researching this brings is in itself perhaps as valuable an experience as actually achieving the goal. If I had bought all of my bikes as perfect completed restorations I would likely not have gained any of the incidental knowledge which struggling to learn about the bikes has now blessed me with.
I believe if I owned vintage cars, this would be my same basic attitude. I would not hesitate to toss in a new Sears battery, a new set of Michelins, new spark plugs and brighter headlights. Even though I knew this is all simply wrong, I'd happily continue to pamper, polish and care for my cars,... but above all, to ride them as much as possible.
Maintaining our bikes is essential; this does not exclude riding them. A next consideration should be finding suitable future caretakers for them - whether to heirs, or perhaps a young local bike mechanic who shares our appreciation for a particular bike, or even a collector on eBay.
I do hope that other collectors' bikes do not rust away simply because little Johnny who'd unappreciatively inherited grandpa's bike will never value it. I fear this is what has happened to the millions of the fine bikes which were naively passed on to a favorite relative, but are now scrap metal. I would never Will one of my bikes over to my younger brother. I love him dearly, but I have come to accept that he simply does not have, and never will have, an appreciation for either bikes or cycling.
If anyone ever does build a public Classic Lightweight Museum, here in the USA, please do let me know. Gifts or permanent loans from the collection (or estate) of Yours Truly will always be sincerely considered. But, such an ossuary, except for some few very rare individual bikes with historic provenance, I would consider an inferior choice to having any bike still joyously ridden... by anyone!
Bob Died-With-His-Cleats-On Hanson,
Albuquerque, New Mexico, USA