You're right about that. Unless we see a seismic shift in the approach to personal technology on both the manufacturing and consumer end, no wearable will achieve this. By current definition, one of the core values of personal technology completely precludes this-- i.e., it is always best to have as recent a version as can be afforded, since each generation represents a significant improvement on the previous one. With that as the case, they're fully mutually exclusive. Do you cherish the bulky 80s portable phone or videocamera your dad had? Do they see daily use in your life? Most people will say no.
However, it's possible --both to achieve heritage and heirloom status, and for reasons of ecological sustainability-- that the personal technology market (and wearables specifically) will try to get around this somehow by offering internal upgrades without the external case requiring modification. Some have suggested this will be possible with the Edition, and while I don't see it happening yet, in the long-term, it could happen.
If it does, wearables should be able to achieve these things, which would be an even greater blow to the mechanical watch market.