The phrase "living standard" is an oxymoron, invented by the incumbents who want to pretend they're supporting standards while weaponising constant change to keep themselves incumbent.
A "standard" should mean there is a clear goal to work towards to for authors and browser vendors. For example, if a browser implements CSS 2.1 (the last sanely defined CSS version), its vendor can say "we support CSS 2.1", authors who care enough can check their CSS using a validator, and users can report if a CSS 2.1 feature is implemented incorrectly.
With a living standard (e.g. HTML5), all you get is a closed circle of implementations which must add a feature before it is specified. Restricting the number of implementations to one and omitting the descriptive prose sounds even worse than the status quo.
I think something like a reference implementation (Ladybird, Servo or even Vaev maybe?) getting picked up as the small-web living standard feels like the best bet for me since that still lets browser projects get the big-time funding for making the big-web work in their browser too. "It's got to look good in Ladybird/Vaev/etc".
An idea: a web authoring tool built around libweb from Ladybird! (Or any other new web implementation that's easily embeddable) The implied standard-ness of whatever goes in that slot would just come for free. (Given enough people are using it!)