I don't think Brawn will leave. I've read somewhere ,that with the arrival of Lauda, Ross will have more time to work with the team. I mean the core of the team, to work directly with the engineers, wile Lauda takes the management like PR, marketing and other stuffs, witch needs plenty of time and has nothing to do, with the team performance.
If Lowe comes, IMO has to be somewhere in the technical department, but there are so many peoples. The time will show anyway.
My eyes, for now are watched in the first car presentations. CAN'T WAIT ANYMORE!!!
Best Regards.