They have, however, indicated that only "some" phones will be unlockable "sometime" after 4.2. They have not said which ones. And of course, all this is subject to change. 😉
Yup, in order to "keep the baseband", you need to have already "had the baseband" to start with, then use TinyUmbrella to update to 4.1 a special way that you can google the documentation for. You cannot downgrade the baseband.