So, a policy appropriate to crypto currencies could be to target a steady growth in nominal transaction fees. Have an initial booting up period where anyone who can bring in a certain amount of hashing power, brings it in and gets coins. It is a pure mordor coin during this initial period. After that (2-3 years, maybe, anybody have any ideas on how to determine when a crypto currency has stabilised?), the targetting mechanism takes over.
The initial bootstrap is tough. I was thinking 3 years. However, instead of pure mordor coin, the "early adopters" would get multiples of the coin award. Perhaps 10x for the first 4 months, then 9x, and so on until the last 4 months at 2x. This would hopefully be enough time to see a reasonable transaction volume and distribution of money among many people (while yes, giving it a slight pyramid distribution to encourage adoption that quickly flattens out). Then flip the switch and people no longer need to mint to get free money. Might be a big deal like the first bitcoin halve, and merchants would be encouraged to start getting in the game.
If the transaction fees paid in a certain interval of time (maybe a week or fortnight) exceed the level target, then automatically lock up a percentage of the money in every account. Coins that can be used now, lets say block height 99, get locked so that they can't be used till block 149. Ownership is maintained, but usage is constrained
I'm sorry but I think this is a terrible idea. You propose the exact opposite of what you should when the economy is expanding--you are strangling it instead of encouraging it. All to prevent price inflation
temporarily if something other than expansion is happening (and cause deflation if it is expansion). Assuming the currency creation base is stable, the value of the money should continue to oscillate around that point. Hell, even without the idea of price stickiness, merchants in a system like Decrits would not need to constantly reprice because of DCR->fiat fluctuations if they could be fairly sure of the stable currency creation base. This will take time and market penetration though.
Messing with account balances or locking coins is going to leave a terrible taste in everyone's mouth, and I don't think it accomplishes anything worthwhile.