I think it could be proven pretty easily that the WT has lied to its members for decades.
What if a number of former JWs banded together to prove the WT's policies cost them large sums of money over the years (due to the discouragement of education and the idea that one shouldn't invest in a world that's going to end soon)?
If we were rewarded with money, that's icing on the cake. Personally the real purpose of such a lawsuit to me would be to cripple the Borg.
How viable is such an idea? And if not, what might be a realistic alternative plan?