This pertains to sites like mybitcoin.com and not wallet.dat.
Is it possible to have a decentralized wallet that uses BTC as a base? BTC -> DonkeyCoin -> Everybody uses the fast Donkeycoin M1 for shops. The donkeycoin can be converted into BTC by the user.
BTC is sent to donkeycoin. Donkeycoin stores the BTC in a block chain. A new block chain is used for say 1 month, before it is deleted. The donkeycoin might automatically be sold to BTC temporarily, then the new money lioncoin is created. Why do this, to keep the block small and fast as possible.
I notice there is a list of the 100 largest wallets. That gives hope that the block.dat can be cleaned out. As all the new owners could be placed in a new block and the old block can be ignored.