I've bought NAME THIS ALCHEMICAL BOOK because I was curious about the ideas it contains, and I was not disappointed. I've incorporated many ideas from it into my Hot Springs Island game I'm running with the Into the Unknown system (5e-b/x hack) and, with a bit of tweaking, it works like a charm.
This makes me very interested in HMtW, assuming the system will have a similar rules-light style. The Obsidian Publishing idea seems great as well. I love the idea of combining a box set (multiple small books at the table) and the Obsidian Portal which I would use to reference rules during play - I always have my laptop with me when GMing for faster rules reference, music, note-taking, rolling heaps of dice quickly, etc.
The only question I have right now: is HMtW going to be focusing on the megadungeon experience exclusively, or will there be any subsystems included that deal with overland travel / hexcrawling?
I'm definitely keeping my eye on your project. Good luck!