This includes seamlessly migrating wallet keys to a quantum resistant scheme without end user intervention? Seems that users would need to do a kind of transaction using existing keys to new wallet/key pair?
We know how to construct kinds of forward compatibility that could allow being spent with a new scheme but the specific scheme would have to be set in advance so they users could generate the future keys at the same time the generate the current ones. And, as mentioned, the existing choices aren't that great (for this application).
If Satoshi Nakamoto did lose his keys to those treasure trove wallets, those will be up for grabs, as will anyone who lost keys.
Perhaps hoarded encrypted PCAP's aren't the only motivator for quantum opportunists.