The first problem is that any hard fork, is not Bitcoin. Only soft forks can be bitcoin. So any discussion of tail emissions, is a discussion about creating a shitcoin.
There was a lot about demurrage I didn't like as well, but some concept of using part of transaction fees to put into a subsidy pool seems workable to me, although it would be voluntary.
The first problem is that any hard fork, is not Bitcoin. Only soft forks can be bitcoin
It's easy to prove this above is false statement.
Peter Todd was right long time ago: Bitcoin will die without the solution ("tail emission, demurrage, or something else entirely")
"Milton Friedman originally proposed a fixed monetary rule, called Friedman's k-percent rule, where the money supply would be automatically increased by a fixed percentage per year. Friedman, for example, viewed a pure gold standard as impractical. (...) if the growth of population or increase in trade outpaces the money supply, there would be no way to counteract deflation and reduced liquidity (and any attendant recession) except for the mining of more gold" ( https://en.wikipedia.org/wiki/Monetarism )
halving means: mining of less gold = strongly reduced liquidity (strongly reduced number of transactions)
reduced mining + reduced transactions = network security in spiral of death
Q.E.D.
And regarding hard fork... Bitcoin may be also out of sudden in a deadly risk from quantum computers. In such circumstances everyone (or: almost, i.e. everyone who cares) - would immediately download a quantum resistant, freshly released bitcoin wallet, no doubt. In deadly danger: hard fork is Bitcoin as well.
These two dangers are similar at least in one aspect: both will cause a spiral of death. And of course - widespread consensus would be the best scenario, but from the other side: a hard fork always shows retrospectively, who was right (like by BCH turmoil in 2017)