These are good points and similar in ways, basically it seems it will eventually fall on the type of bike and rarity. Most will have some kind of value (which is fine), but few will be major money or highly coveted. Some bikes are bought on the emotional aspect (prior ownership/childhood), some for current or future profit, some just because riding is a passion, and others own a current model and want something Old School Cool. The things is; there are low, mid and high range bikes varying in uniqueness and quality. And there are people in each income range. That's what makes this difficult to pin as it is a broad spectrum.

There will always be bike collectors. And the seventies and eighties pretty much changed the world of riding. Not only Road, but Bmx and Mountain, so that should stand the test of time for some special collector items. Not saying all, but a decent amount.

There are antique type special bikes that have some value, but I think not many people go after the sixties or earlier due to the cotter crank, inefficient parts, too heavy (even for steel is real guys :-)) etc. I have seen bikes like Schwinn (sorry guys) boom (ties to history) but that crowd got older and those were either kids bikes, cruisers that you rarely ride, or from what I recall as a kid (again sorry), lower end bikes (Paramount and some road exception). The other thing I noticed is BMX. I rode BMX into my early twenties until family duty called. Being young I thought I would never stop, but I did. I saw the prices of bikes when guys my age started having flash backs and they sky rocketed. I personally could not bring myself to get in on that, as I knew I would not ride. But now, that crowd is thinned due to them being small bikes and I see decent BMX on CL here and there. And they're not 2k and up, but in the hundreds. There will always be some highly sought after, but the collectible ones are thinned to mostly the best of the best.

Anyway that's all I got, my .02 :-) Just my opinion from what I have seen.