The big problem is that the most you could likely get out of a complaint would be a refund, plus interest. And on giving you the refund they would also remove the EAP features, though you could buy them for $6K, maybe you could get a deal on them. So it would not be much of a lawsuit, you would need a class action where they had to offer the refund to everybody. But right now I am not sure how many would claim it.
While Musk regularly predicts FSD will arrive this year, the written statements from Tesla don't say that so you would have to convince the court Musk was making a promise, rather than just making a prediction or expressing a hope. Hard challenge to prove. I think you could make a claim that autosteer on city streets has been "coming soon" for much longer than any reasonable definition of soon.
And get your refund.
To get more you would have to demonstrate, "I never would have bought a Tesla if i didn't expect I would get FSD soon" and then they might buy back your car. But I think this would be hard to prove.
But if they are forced into refunds, I think they will be able to stop most people from getting them. I only paid $2K for FSD, do it's barely worth it. They would sweeten the pot for people who don't refund, like rush up a new feature available only to those refund, an actual useful feature, not smart summon or other useless stuff. They would promise this for the future (but actually have to deliver it.)
So it's not clear what you would get.