Here is the reason of this post: #84108 :)
First I need to define meaning of term "global adoption" used here: Most of countries are in the place where El Salvador already is, i.e. you can fly worldwide having only LN wallet in your smartphone.
  1. We do know we are still before the global adoption and we do believe it is inevitable.
  2. We do know such global adoption would increase price and marketcap of Bitcoin by order of magnitude, at least.
Demurrage implemented in Bitcoin - would decrease purchasing power of your holdings by e.g. 0.1% per year, in the moment you decide to spend it.
Because these two statements above are also obvious to almost all Bitcoin stakeholders - most of them will try to hoard Bitcoin until global adoption and NOT TO SPEND. Additionally it will increase pressure to use Lightning Network whereve it's possible, as LN viewed as "demurrage tax free" zone. And all above - due to still extremely appealing 10 years risk/reward: 1% tax versus 1000% increase. And this way we won't get the result we expect: miners won't have significant source of income from demurrage to keep the security of the network untouched. Even Bitcoin can't beat the human nature.
If the first "destructive halving" (i.e. network difficulty was not able to recover during long four years after given halving) will appear before the global adoption - the 0.1% demurrage is simply not the answer and any effort placed here will be futile. Before global adoption - the only answer is 0.1% tail emission, preferably with Milton Friedman's k-percent rule concept.
I have something yet in fact, which fits to the last part of Peter Todd quote: "tail emission, demurrage, or something else entirely". Something else entirely, the only problem is I'm not clever enough to fit it to Bitcoin... :)
The root of problem we need to realise is we have no interconnector between two separate worlds: digital Bitcoin and the real one. In the LTE radio network there is something called "open loop / closed loop" control mechanism, which reacts for slow and fast types of changes in the air channel. And regulates the power and other radio parameters accordingly there.
The analogous idea is to swap current: difficulty adjustment towards constant coin supply (i.e. regulation of difficulty to keep constant block time preconfigured by developer)
for: block reward adjustment towards constant security behind the network, in terms of purchasing power (i.e. regulation of block reward to keep constant network difficulty configured by developers, let say: once per year? )
This way: setting/keeping constant security behind the network, in terms of (calculable!) purchasing power (in cross-sectional prices of gold, Big Mac, recent iPhone, etc) - would be an slowly reacting open loop
and algorithmic mechanism with negative feedback loop that executes the order from developers by constant (smooth and w/ critical damping) regulation of block reward - would be a quickly reacting closed loop
This would constitute stable, transactional money, with stable security behind, with stable equilibrium between two groups of opposite interests (miners and stakeholders) and with embedded option to smoothly correct the overall direction the network goes (also in case of emergency situations/unexpected events like disruptive hashing hardware appearance, global economic turmoil, etc)
And last but not least, such solution could even induce negligible reward periods, when the miners' income from transactions is high enough to keep the whole network security untouched. So even people who insist that current emission curve is great and fees will be enough to keep current level of network security - should be satisfied as well :)
So... perfect concept, but even less probable than swapping halvings for Milton Friedman's k-percent rule.... Or, maybe I'm wrong? ;)
Anyway, times of first "destructive halving" will be interesting...
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.
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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)