Pretty sure I answered this on the thread somewhere (but possibly another discussion) but I recap: Efficient blockchain with significant user base and innovative fee-free model. In-built social layer is useful even without on-chain rewards (and requires RC and therefore Steem to use). Current and future third party apps/games driving demand for RCs and therefore Steem. SMTs and communities with their own reward pools (driving demand for RCs and therefore Steem, also using Steem as reserve/bridge currency). SPS as an alternative rewarding mechanism (albeit all evidence points toward smaller/less inflation being better). Reward pool could remain even if not funded by inflation; it could be funded by advertising and fee revenue (though I think this works better on a subcommunity and not global basis; just my opinion, not necessarily right). There are probably other reasons. There are roughly 75 blockchains with currently numerically more value than Steem and few if any of them have a 'reward pool' (I think none) and Steem does many things better than many if not most of them. The value gap is a challenge to the idea that Steem's current setup and assumptions about model as a value creator vs. a value destroyer.

Another possibility would be to keep the pool but simply make it smaller. The 8.5% inflation is part of the challenge as claimed by this post. The post claims inflation should be 2% or less. There might be a bit of room in there for a smaller reward pool, while still having one.

If we continue on the current trajectory, the 8.5% will eventually go down to 1%, and the reward pool will be a lot smaller, but the reward pool will still be 75% of total inflation even then, meaning chain security declines to 0.1%. Relative to other chains that is probably too small or at best a big gamble.