So this is a trend I'm following closely in my company. Question - why are you only focused on WordPress? In the grand scheme of things, WordPress is an irrelevant participant, a spec in a dust storm. I think the idea of sustainability is great, but if the goal is sustainability, then it would be short-sighted, irresponsible, foolish even, to focus on possible solutions without removing WordPress from the question.

You said in a previous response to Ryan's comment "we need to think beyond that ... ". I get what site I'm on, and I'm 100% positive if I say to you, "Recommend me a solution to use for a non-blog website that I want to maintain myself", you'll wrongfully recommend WordPress - I get it, I know where you stand and where your target audience stands but WP has no stake in this argument. Hosting providers and people are the ones who have the stake in this. If you're asking people to think bigger, then you also need to think bigger, and get yourself out of the WP bubble. My comment probably won't get posted, because it'll rub the die by the WP sword fan boys the wrong way, but the problem is quite simple to solve, and again, WP has no play in this. Why is it being discussed here, and not on a more visible platform? You'd probably get a bigger response if you did. All the best.