One year is far too fast a timeout.
I think DMDv4 is proposing accounts idle for ten full years start to evapourate over time maybe or something like that, but any such ideas rebel against the immutability of blockchain.
Bitcoin seems to work fine with uknown numbers of "lost coins" out there.
Not to mention that any such rule could force e.g. Satoshi to put lie on the line to avoid having coins in effect stolen, if Satoshi isn't already dead.
If you are up for coding though there are glitches in HORIZON that could do with fixing, such as its so called currencies subsystem is broken enough we ended up having to catagorise everything as assets.
-MarkM-