We can discuss ways that it might be possible for all of us to win, but in the end I only care about whether I win, and that should be the attitude that everyone takes. So unless we have a forced win for everyone, we should be expecting people to deviate from any plan we come up with, if they judge those deviations to improve their odds of winning.
I'm not saying it's bad to try to come up with a plan that makes us all win, but unless it's 100% guaranteed (which it probably isn't because we're not sure how players turn black and whether that gives them all three win-cons or what), there is a good chance that someone will screw it up by fighting for their own win-con (which is what they should do), so we shouldn't be relying on it. Instead I think it might be best if two alignments team up and try to fight off the third. If the Reds and Yellows agree to take out Blues, it might be a lot easier for all of the Reds and Yellows to win than if we try to get everyone to win. I don't know that this is the case because I haven't spent a lot of time thinking about it, but it seems like it should be.