You may want to consider an additional throttle on emission, based on hashrate.
Hashrate is, in part, an indirect measure of market demand for the coin. The higher the hashrate on the Proof-of-Work algos, the more there is demand, and vice versa. Thus, it makes sense to scale down emission when hashrate is relatively low, thereby further extending the distribution period for the coin.
For example, calculate the average hashrate seen in every 24 hour period going back one year. Choose the maximum of these values as the historical "peak hashrate" and use it as the denominator for a subsidy scaling factor (SSF). Take the latest 24 hour period as the "current hashrate", and use as numerator. SSF = peak_hashrate / current_hashrate. Then, over the next 24 hour period, whatever reward is in the halving schedule gets scaled by SSF. It will likely be reduced, and only be the full reward if current = peak hashrate.
This coin emission modulation could be applied independently to each of the 5 PoW algos
we are actually working on that now. we did a twitter poll and we are going to extend the last year of pow to 6 years, with more halvings
This is great. It makes alot of sense, and having the community support in a democratic fashion is very good too.
I suggest an additional layer of coin emission reduction, which would depend on hashrate. Most halving schedules are mechanical and rigid: every "x" blocks they reduce the reward, never to go higher again. That's fine, but with a hashrate-modulated scaling factor, those 6 years, could, potentially, be stretched 2x, 3x or even more into the future.
It would depend on the hashrate seen on the network. If hashrate was always growing thus always at max, then yes, the emission would be completed in 6 years (subsidy scale factor or 'SSF' is always 100%), but.... if the hashrate fell at times, then during those times, not 100% of the scheduled reward would be given, ( SSF at less than 100% ) it would be scaled
dynamically (effectively reserving coins for emission into the future).
Of course, to respect emission limits, the halving points would no longer depend on number of blocks issued, but rather total money supply issued. This would have to be kept track of, but is easily done.