Ideally we simply give proper attribution and prestige to those sharing ideas. But if we could do that the copyright system wouldn't be needed.
Personally, I always threw around 28 + 28 in my head (given that life expectancy in the 18th century was vastly different), with a slight twist: only the original copyright author can renew the term, and the copyright ownership in this context needs to be some sufficiently small group inventors. Anything owned by a corporation larger than X people won't renew.
So any potential transferral or relinquishing of ownership needs to at the very least appease the creator(s) so these corporations can get their other 28 years of their terms.
Personally, I always threw around 28 + 28 in my head (given that life expectancy in the 18th century was vastly different), with a slight twist: only the original copyright author can renew the term, and the copyright ownership in this context needs to be some sufficiently small group inventors. Anything owned by a corporation larger than X people won't renew.
So any potential transferral or relinquishing of ownership needs to at the very least appease the creator(s) so these corporations can get their other 28 years of their terms.