Look at how successful the mobile-friendly push was at getting everyone from vaguely talking about responsive designs to doing it Right Now! Every user-visible benefit of AMP would happen following your comment – increase the weight for page load time/size and add a standard pre-fetch mechanism[1] which would close most of the gap for the CDN hosting.
1. i.e. the top n results will have rel=dns-prefetch tags hoisted into the search result, the top result (or visible/hover/etc.) will have the first rel=preload html/style/script tags hoisted.
If Google ranked load-time/page-bloat much heavier in their algorithm, and started punishing bad pages, then sites would adjust.
I currently see very little action from Google in this direction.