PSR-4 naming convention is something I think should be included in the Wordpress coding guidelines. Autoloading is often considered a core php functionality these days.

I wonder what other changes to WordPress coding standards will be necessitated by this single change. My father referred to this sort of thing as the "Pillow Effect" where he would end up remodeling the entire living room after my step mother goes shopping for a new throw pillow. (The new pillow doesn't really match the current sofa, necessitating a new sofa, the new sofa doesn't really look right with the old coffee table, so a new coffee table is needed, and so on & so on...)