I'm actually in the middle of writing a post about this topic, but my current opinion is essentially that Steem shouldn't have a reward pool as it's too nuanced towards the needs and wants of its too diverse group of users.
Let Steemit issue a new coin for its own use using SMT preserving all the rules and communities. Let it prosper or fail on its own. Community will choose to stay or leave on their own judgement.
Instead, I would propose something similar. Move the current economic model to its own SMT and those who disagree with it or believe other rules will be more successful can do so with their own SMT. This would also prevent our civil war around HF21 EiP.
Inflation should be minimum. Even interest for SP is not necessary(currently 2.5% or similar). Paying for witnesses may be the minimum.
I agree. I've written a post about this few months ago (https://steemit.com/steem/@therealwolf/steem-2020-reducing-inflation-to-less-than-2). This didn't include the SPS, but we should be able to achieve an inflation pool of less than 3% and probably even less than 1% of the next few years.
Steem Power for What?
For future Steem, the idea could be to advertise the vesting inflation (probably also increase it a bit) or to remove the staking inflation completely.
Use case for Steem(power) would be for resource credits and as the base layer for SMTs. For example: Create an SMT, burn STEEM.
Anyway, important conversation to have. Steem is a tough thing to manage as it's quite decentralised in comparison to almost all other projects in existence. And we're currently lacking a real vision of what Steem is supposed to be.