We conclude by noting that the analysis presented in this paper breaks down when the
block reward falls to zero. It suggests that the cost of block space is zero; however, this would
suggest zero hash power, which in turn would suggest that transactions would never be mined
and, paradoxically, that no block space would be produced. Happily, questions about the
post-block reward future can be explored at a leisurely pace, as we have a quarter-century
before it begins to become a reality. Into the distant future then, a healthy transaction fee
market is expected to exist without a block size limit.
It makes perfect sense that averaged across all miners
cost per byte ~ inflation rate (et) where
t is propagation time and
~ means proportional to. Because difficulty adjusts, thus hashing cost rises to match the block reward (i.e. inflation rate) multiplied by wasted hashrate losses due to orphan rate.
It is independent of the amount data in the block (meaning there is no cost constraining amount of data to put in a block). That is because the equation he chose is modeling everyone having the same orphan rate, thus it models that no miner attempts to use a smaller block size than the other one.
But miners will strategically employ this block size choice and it turns out that it is a power vacuum with winner-take-all property that forces a cartel to use large blocks as a weapon against those not in the cartel.
So IMO he hasn't entirely acknowledged his error. He noticed there were problems in his analysis, but he didn't entirely home in on the holistic conclusion. His model is meaningless. It makes no sense to model average orphan rate as a limiting factor providing an equilibrium, because miners have incentive to do whatever it takes to reduce the waste of their individualized orphan rate and they can do so at their advantage by not including the minority in their cartel, so that the non-cartel minority has a very high orphan rate and the cartel has an ultra low orphan rate. The only equilibrium is due to centralization of control.