You assume bad intent while there is no proof of that at all.
We don't know when they internally made the decision to no longer aim for an offline mode.
For all we know they been trying until shortly before the announcement. Maybe you are right, but you simply can't know if you are.
Heck, if they knew sooner it would have been in their best interest to say so sooner and have this backlash over with long before the launch.
To assume they would do it now, shortly before their big event, out of some evil plot to mess with people is just not a realistic assumption.
Projects goals change all the time, and this was a kickstarter project. There is no guaranties when you back a kickstarter.
So a lawsuit is not realistic at all, there is no chance at all that a lawsuit could force them to change their plans, and it shouldn't either.
Heck, some projects got funded and never delivered anything and didn't get a lawsuit either.
At least with Elite Dangerous we know they are doing an amazing job at really bringing the game.
They have been very reliable through out alpha and beta, and been very respectful toward their backers.
And just for this one thing you act like they are the scum of the earth.