> Devising a new schema based on SQLite would allow for current features that are being jerry-rigged into the attributes to have their own real place in the database

Perfectly possible with XML too

> An SQLite based store is one of the most tested and optimal formats for document and application storage

It's optimized for things that largely don't matter for password storage. The testing is admirable, but there's no issue of keepass clients crashing or corrupting data so again, not very relevant (probably because of low concurrency, simple writes etc).

> A switch this big is a major chance to fix the governance structure and align it more with a democratic consortium than a benevolent-dictator-for-life style of project management

You don't need a technical change to solve this. In fact, a fork that would fracture clients is the last thing you need when making governance changes.

> So many quality of life features can be added where the old schema disallowed it

All of the features they list can be achieved with an XML format. The format isn't what's holding them back.