[mariuolo]

Perhaps someone can clarify a point for me: I'm under the impression that whatever the foundation or project that adopts Thunderbird, it would have to be half-rewritten to get rid of its legacy (Gecko/XPCOM/XUL) codebase.

Is that correct? Has anyone estimated how much time/money/manpower that would require?

[pgquiles]

Mozilla Corp is currently hiring a contractor to do precisely that.

https://careers.mozilla.org/position/ohUW2fwT

IMHO Thunderbird should replace: - Gecko with Blink - XPCOM with normal plugins (I don't think anyone is making any real use of the unique features of XPCOM, e. g. the universal binary interface) - XUL with QML/WPF/alike.

Qt would provide a full-stack alternative: - Gecko -> QtWebEngine - XPCOM -> QPluginLoader - XUL -> QML

Maintainability and performance would increase exponentially.