This is a really interesting distribution mechanism and I'd love to see what it looks like in practice, but I have a hard time seeing it as a replacement for Steem from what you've written here. I'm not clear on the functionality of your "simpler blockchain," though; are you envisioning writing entirely new code that could replicate the functionality of Steem in an emergency? If so, why not start an independent chain? I guess you could do both.

I agree that the Steem codebase is a mess, but it's not an unsalvageable mess, it's just that there's not a lot of motivation for "forensic programmers," so to speak, to take a hack at it. If the original authors were to vanish, and there was motivation to pick it up, I'm reasonably confident that the codebase could be maintained.

Assuming MIRA comes through, that should make the node situation considerably better.

So I really only see a drastic backup as necessary if Steemit Inc. were to become unusable during a development emergency of some sort, which is unlikely. And even then the chain state could be saved and the chain paused while the emergency was addressed; even a month or two of downtime would probably be seen as a superior alternative to wholesale re-envisioning of distribution.

I do think it would be really interesting to try running this as an experimental parallel chain, and see what the userbase thought of it, not pitched as "better Steem" but as a new chain with an unusual airdrop. I don't know if you see that as worth your time as much.