It seems to me that ETH1 is the wrong place to be doing this due to interaction required between ETH1 and ETH2 to implement. Withdrawal credential rotation from BLS to Eth1 is an alternative proposal that runs purely on ETH2, and allows withdrawal credentials to be set to an ETH1 address. If that address is a smart contract it allows ultimate flexibility for control of withdrawn funds.
Are there any benefits, in your view, to the above proposal Vs the one I linked?