"tragedy of the commons" - solvable by RBF?

I'm skeptical if this is actually a problem because of higher orphans rates for larger blocks. The idea is this: What if a miner was guaranteed block after block after block ? What transactions would they include? In theory they would find an optimal minimum fee to include in their blocks. People who guessed below this fee would not be included in the block. In the next block, since their demand for their transaction still exists.. they would raise their fee in theory. This may then meet the minimum threshold to be included.

The point is this: Since a miner is not guaranteed block after block an individual miner may undercut his fellow miner by including every transaction that had a fee for maximum profit by making his block large as possible. What incentive is there for him to create a minimum fee if there is no guarantee that the next miner will not follow it?

solution: if a miner detects that a transaction is under the minimum he can not include the transaction. The next block, if the transaction is an RBF transaction then a part of the fee for that transaction (which would be higher) would be split between the miner of the last block and the current miner.

problem: this wouldn't work for non RBF transactions. Is the fee enough to be split and make it economically incentivized?. Is this possible to split an RBF fee in this manner through a soft fork or only hard? would you have to incentivize RBF transactions somehow since it doesn't work for non RBF ones? Can the coinbase transaction pay out to the old miner as well using the last payout address or would that be too complicated?