Allow some API to be produced that, as long as a browser supplies the calls, will replace IE's rendering engine, allow system builders to produce windows bundled with any browser technology and remove IE as a requirement for receiving updates.

For the latter case, have a separate application to do the downloading. There's no need for it to be an internet application embedded in the browser (except so far as to make IE with it's ActiveX technology a REQUIRED part of the OS). When I use Linux, clicking on an rpm calls up the packaging manager and the browser is merely used to download the package to pass on to the application.