Redbull Honda. Has a ring to it.
I believe McLaren has an exclusive contract for the Honda engine for 2015.
It's not as if Ferrari or Mercedes will be tripping over each other to provide Red Bull with an engine, so who?
I could see a scenario where Ferrari may well supply Red Bull engines. Ferrari have for a long time expressed concerns with the direction of F1 (budgets restrictions, no testing, getting slower and slower, not leading edge technology anymore). At the same time LM is on the rise and there are more marquee teams (of the nature that Ferrari want to compete with) racing there. Ferrari have stated that they wont race directly in both and that they are looking at LMS racing. If Red Bull signed up for long enough to Ferrari engines, that may be a way for Ferrari to make the transition - if things keep pushing the team in that direction.
Geez Spanky, I know you've been a bit down on the sport lately but come on, if Ferrari were to leave, do you think they'd win in LMS the way they have in the past in F1? The competition there is fierce and it's just as much about the driver teams as it is about the cars, that's something that goes against the grain at the scuderia. It's nearly as expensive as F1 and they've be going head to head with teams that have tenfold Ferrari's budget. Additionally, LMS is for teams to develop their road cars, what's in it for
Ferrari to compete against Nissan, and Toyota? Porsche and Audi would never allow Ferrari to dominate and there is so much unpredictability in the sport, so even a "garagista" team can win. F1 may come to an end, but not because Ferrari abandons it. I'd counter, Ferrari leaving F1 would be seen as them leaving with their tail between their legs, especially after a long period sans championship.