Thanks for your reply. Having fees be implicit in a transaction as opposed to existing as a separate output saves space in the block (and in the utxo set), but maybe in the future people will just pay their fees to an output of <k blocks> OP_CSV thereby emulating (with k = 100) the traditional incentives.

It also is interesting to think about what might happen if people started extending k to longer durations.

Rationally, for larger k, this "explicit fee output" would cost the sender more sats (time value of money) to get the transaction confirmed (assuming miners would even be on the lookout for such transactions with these outputs), but if the mempools were to have a lot of otherwise equal value transactions with different ks, then we might be able to get a near-real-time gauge of miner time preference/myopia.