In answer to your question of a(n) obviously inactive BTC wallet is impossible for some to maybe fathom at this point but lets assume this. BTC makes it past the point of a new block transaction and starts relying solely on miner fees which I believe if Im not wrong is set to happen sometime around 21(something)AD, we could most likely assume that anyone holding a BTC Wallet at that time (if showing no activity for say 50-60 years) is probably lost, and there therefore (IMO be reclaimed) after a alert to the wallet hodler.
I am aware that is a long off worry and one that might not ever happen but I just thought Id put it out there.
You can not assume a finite currency will survive more than several centuries, if for not other reason it will get lost. Especially with one so finite and complex as BTC
Coins should remain in wallets for 50,000 years and maybe that's what their owners are aiming for.
Forking to grab them sets a 100% unacceptable precedent and it would shit on everything bitcoin had built over the years. You could never depend on its immutability again and that's its prime purpose.