From my understanding, nLockTime is like a delay timer for transactions, and miners can't confirm them until the set time is reached.
-snip-
1. Can a transaction with nLockTime be replaced with a new one that has a different nLockTime value? What happens if it gets replaced?
2. If a transaction with nLockTime is stuck in the mempool because of low fees, can I use RBF to replace it with a new transaction that has a higher fee?
You can't correlate RBF with nLocktime since a non-final nLocktime prevents the transaction to be relayed by nodes,
So it's either saved by the user locally or saved in the wallet as a local transaction if it has such feature. (
not broadcasted)
While utilizing RBF for transaction replacement (
bump fee) is for
unconfirmed transactions that are already broadcasted to the network.