We don’t care about “replacement”, or any of the policy and pool antics that are currently ongoing. We just store a tx if it has sufficient fees (configurable) to guard the store.
This implies that if a tx creates a conflict with a stored tx, the net mineable fee must be a min increase for it to be accepted, strictly for DoS protect. Packaging is this also considered, but not in the way Core has implemented it. I posted our concept of that to bitcoin-dev a couple years ago.