I've kept most of my old stuff but I have, over the years sold/traded-in/given away:

Praktica L
Praktica LLC
35mm/50mm/135mm/400mm lenses for above
Olympus RC
Olympus OM2n
Zuiko 75-150mm F4 and 300mm F4.5 lenses
Kodak (126) Instamatic 200

...oh, and a Leica M4 50th Anniversary model with 35mm Summicron (probably worth more than everything photographical that I own now!)

Aaah nostalgia, comes to us all in time.

In respect of cameras I am sure that younger members coming into photography in the digital age, will in later years reflect on years gone by. The means of recording an image in 30 years time will no doubt be significantly different from that we use today. In threads on this forum we have comments on the introduction of TTL metering for example. Would not even think about it today. So that technology advance only really has relevance to those who used cameras before its introduction. Similarly I think that other than for collectors there is a life span to old film cameras. 50 years from now and very few people generally will have any experience of film.

I think the current Pro DSLR's will then be viewed in awe. Veritable heavyweight monsters. Viewers of archive film may well have seen pictures of press photograhers wielding these monsters http://www.cosmonet.org/camera/spgr_e.htm

So in answer to Stephens question I would say yes to keeping nice examples of digital cameras that have some landmark ( personal or development ) status. Pro cameras are usually good savers as in the world in which they are mostly used most lead a hard life so in time nice examples become sought after.

Don