From the toolkits: "JavaScript toolkits enhance productivity but often carry a significant memory footprint that may slow down your JavaScript application. When using a toolkit, try to reduce the toolkit’s footprint to just the APIs that you use in your application."

This somewhat hints to me that Apple will come out with a framework that allows more modular includes or compiles similar to closures system. This is somewhat a hit to jQuery's "all-in-one" setup.