So apparently there's like 4-6 million bitcoin that are lost and gone? Just curious if there was any ideas or plans to update the protocol to replace the lost bitcoins if there was a consensus, if that is even possible.
That number is speculative, you cannot really know for sure how many BTC's are lost and lost forever. Take note that there are coins that have been in a particular address for a very long time and have not moved, but some people think the coins are lost, whereas the owner still has the keys to the funds and just does not want to move it or spend it yet.
There would be no update on the protocol that would implement what you have suggested, lost coins would remain lost, and if you don't want to lose your coins, work on your opsec and security.