This is a quote from the book "On Zero Confirmation Transactions" by Chris Pacia are we at today?

Since previous core maintainer Gavin Andresen and Mike Hearn have now been purged from core development it seems the developers are hell bent on ramming th
rough replace-by-fee.

An “opt-in” version has already been rammed through, without consensus, and with almost no discussion. The opt-in version only enables replace-by-fee on tr
ansactions containing a sequence number less than the maximum. Technically, retailers will be able to detect unconfirmed RBF transactions and reject them (making the fee bump part of it useless)...
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