I think that Toyota's exit from F1 was long decided. To car manufacturers F1 gave the chance to show that they are capable of developing better technologies than others. Since Toyota considers Honda to be its biggest rival it was an obvious decision by Toyota to quit it. They only stuck around for an extra season to see the car's potential as it must have been already developed at the time of Honda's announcement.
I also think that a lot of you guys are suggesting that F1 should move towards an even more spec series strategy for cost cutting, but it'd kill all of what F1 is about. Making engines equal after they have been developed is the bigges mistake I've seen in a while. It kills the whole nature of F1. Teams had a lot of free hand in the development from the 60s to the 90s - until F1 started to be run like a circus - so it is a lie that costs are limiting. It is just that we limited our development so much that it doesn't allow for innovative thinking anymore. When it does... take the case of the current season. You end up with smart teams beating money teams. You will see that was always the story of the winners in F1.