RE: a hard upper limit, with a dynamic limit under it:

I like that idea. Can we drill down on the hard upper limit?

There are lots of people who want a very high upper limit, right now (all the big Bitcoin companies, and anybody who thinks as-rapid-as-possible growth now is the best path to long-term success). This is the "it is OK if you have to run full nodes in a data center" camp.

There are also lots of people who want an upper limit low enough that they can continue to run Bitcoin on the hardware and Internet connection that they have (or are concerned about centralization, so want to make sure OTHER people can continue to run....).

Is there an upper limit "we" can choose to make both sets of people mostly happy? I've proposed "must be inexpensive enough that a 'hobbyist' can afford to run a full node" ...

Is the limit chosen once, now, via hard-fork, or should we expect multiple hard-forks to change it "when necessary" ?

The economics change every time the block reward halves, which make me think that might be a good time to adjust the hard upper limit. If we have a hard upper limit and a lower dynamic limit, perhaps adjusting the hard upper limit (up or down) to account for the block reward halving, based on the dynamic limit....

RE: the lower dynamic limit algorithm:  I REALLY like that idea.