First, anything said about the Turbo before release is not official, it was rumor. Nothing was official until the day of release. Around the time of release, they mentioned that it would be upgradeable to LP. By itself the only way anyone could even think of suing is if the Turbo gets EOLed before it sees LP. With no specific date given, they only have to get the update out before support is ended to meet their statement.
I want LP as well, though for me it's curiosity to see how far off of AOSP the Turbo's build will be. I understand that some are having issues on KK, but those affected appear to be random and in the minority. My device works fine the way it is, and I know some here are saying that waiting longer won't ensure a more stable build. That is not necessarily true. A rushed update will have more issues than one that they take their time on it, that's just common sense. Sure they may get lucky and rush an update and have a minimal amount of bugs, but luck runs out. What if they had pushed a build out earlier for either 5.0.2 or 5.1 because people were screaming for it and then it ended up causing a support nightmare? Again I want the update as well, maybe not as much as some of you, but since there is apparently a rather serious issue so far, I would prefer they concentrate on fixing the issue rather than pushing the update so they can say they did and screwing up my device.
Regardless, what is a lawsuit going to get you? You want money, a new device, both? History has shown that any winnings from such a suit will be negligible, look at Apple's solution for their grip of death scandal. They sent out rubber bumpers that most likely cost them less than a dollar each, and that's from the wealthiest company on the planet. In the majority of these suits, the compensation awarded to the plaintiffs ends up being less than what they put into it. You would also have to show that either you were harmed by their actions or that they willfully misled you. If they didn't think they were going to be able to do what they said and did it anyway, they open themselves up to litigation, and they aren't going to risk that. I seriously can't see how people can't understand that it's possible that they didn't believe that they would have as much trouble as they have. There are plenty of times I went to repair something in my former job and it proved to be a much more involved process to resolve than I originally thought. When it happens, the only thing you can do is put your head down and keep plugging away at it until you resolve the issue, which is what they're doing now. And giving a timeframe for the fix when you have no earthly idea how long it will take is irresponsible. All it does is shut people up until the date arrives and then you have to explain why you couldn't fulfill your promise. How is that more professional than saying "we're working on it"? At least there you're not outright lying to the customers. Unless you can say with certainty how long it will take to fix the issue, it's better to say you don't know but that you are working on it. Otherwise you're just saying what they want to hear to get them off your backs when you know full well you aren't going to meet that deadline.