I think with Redbulls rise of from and there 1st class design team, they will convince Vettel to sign up(allthough if i was horner i would replace DC with vettel after this GP).
With Vettel and Webber in the team rekon they could garrentee 4th spot and probably catch up to BMW.
I don't think BMW will ditch heifield yet, he did some solid job when the team weren't competitive and you can't find a quicker german right now. (timo glock MAYBE)