Red Bull have come a long way from Mateschitz being Gerhard Berger's mate and asking him to drink it in the paddock in the late 80's.Never say never, but a team that has had such success, has invested significantly in its own engine program, and partnered with Ford for "at least" four years (in the latter's own words), isn't likely to vanish overnight.
Even if RB's new power structure isn't as big of a fan of F1 as the previous regime, it's not going to completely throw away that kind of exposure, or brand equity and withdraw completely.
I don't think the investment they've made would stop them selling the team though. Honda spent $1bn on their 2009 race car before running away and selling it to Ross Brawn. Red Bull could sell the team and Ford contract, but I don't think it is likely. They've lost a lot of key personnel over the past 6 months and I would imagine there is some serious restructuring going on behind the scenes, but I think they'll stay for a few more years, even if it is to prove they can win without Newey.