it wouldn't surprise me if toyota left as they have not seen results and their board supposedly has factions that are anti-F1. there was talk a few years ago of the manufacturers starting a breakaway series but i find that to be highly unlikely. even the cachet of the name "Formula 1" or "F1" versus whatever they would come up would change the perception of the public and would make it seem to be an inferior series. i don't think the manufacturers want to try and re-boot the pinnacle of motorsport, they can barely get along as it is.

also, they couldn't join A1 GP because that is a series based on identical cars campaigned by differing countries rather than teams in the traditional sense. it is marketed as the "world cup" of motorsport.

i have said this before but in my opinion the solution to these problems is a rule change to allow customer chassis in addition to the engine deals currently available. for example, if a privateer team could enter F1, buy a chassis from say McLaren and then buy an engine from Ferrari and put that car on the grid this would become a very attractive arena. that is exactly what Prodrive attempted to do last year but was not allowed to. with the advent of a budget cap, customer chassis, and customer engines teams like iSport and Prodrive (among others) could enter the championship and really help mix things up while also being competitive. F1 can't move forward with a grid consisting entirely of manufacturers, you simply cannot depend on them for the long term.