What if the private key is sent after 6 confirmations? So the public key is indexed in the blockchain , and after 6 blocks the private key is sent and then the transaction would be finalized.
So that no node & miner could steal / double spend the coins, gets indexed to the blockchain, and then the private key is revealed, finalizing the transaction and confirming the spending.
Ok, so then how do you plan on verifying the signature? What algorithm are you going to use that takes a private key and then verifies to the sha256d hash of that key without revealing the key itself? You most certainly aren't going to be using ECDSA since ECDSA requires a public key derived from the private key in a different way using elliptic curves.
What do you mean by "finalized"? What happens if the key that is published is incorrect? What if the sender refuses to publish the key?