If there was a system in place where you could "attach" a transaction to another in this way it could solve the problems RBF originally was supposed to solve, which is allowing you to send more to "bump" a transaction. This would be done by making another transaction with a miner fee to incentivize it to be placed into a block.
This already exists. It's called CPFP (
Child
Pays
For
Parent).
If I've received an output from an unconfirmed transaction, I can use that output as an input in a new transaction. I can then pay a much larger fee in the new transaction. The new transaction cannot be confirmed unless the previous transaction is also confirmed in the same or earlier block. As such, the new transaction can provide a larger incentive for the older transaction to be confirmed.
Then, by using CoinJoin techniques, it would be possible for many people to all get involved in the same new transaction. As such, all the fees from multiple payments could all be combined into a single transaction that depends on the earlier transaction being confirmed.