(Last one of the day, I promise.)
For WordPress 3 have Sandbox 2 as the theme core, with all theme designs done as a 'skin' for Sandbox 2. Sandbox 2 to include a skin switcher as in the old days. Each copy of Sandbox 2 to include a PDF of "Sandbox for Dummies" explaining what those dang 'classes' are for, how they are used, and how they are implemented. Complete with examples. Instructions for modifying the core should that be desired.