John makes some great points, which is why I'd like to follow him and see the progression of this. One of us (or a few of us) are going to need to just get down-n-dirty and start building it.
The internet is indeed filled with a lot of sentiment for rebuilding WordPress. Most of us who've worked with WP a long time (since b2) have considered it (myself included).
I'd love to roll out of bed one morning and press a red LAUNCH button that releases a fresh new fork of WordPress to the world that's compatible with most of it's theme/plugin ecosystem.