Sorry for reviving an old email thread. Could you describe what the UX would be like, or how a wallet developer might implement this? Is the intention that someone would open their non-private wallet, and choose an option that slowly siphons their funds into a different app? Why would anyone want that feature?
If the user is privacy-conscious, why did they choose the non-private wallet to begin with? Why wouldn't they just move all their funds to the private wallet so they can continue to use just one app?
And if the user is not privacy-conscious, they would never choose to enable this option, so why would the wallet developer even bother to implement it?
From a product standpoint, I can't see how this would be useful, and therefore I'm not sure why it needs to be a BIP. If I'm missing something, please let me know!
Thanks,