Ron, I think this is the real deal. I was one of those who signed up as a plaintiff with a law firm and filed an individual suit. I was told it would not be a class action. Looks like that wasn't true but, I understand because there were so many suits, the court probably had no choice but to let everyone in. 
The "fairness hearing" is standard in class actions. I think only lead plaintiffs can object to the settlement but that may not be true. There will be a settlement because this figure of $1.51B is a number Syngenta agreed upon. Note that this is just the amount for producers. The elevators, ethanol plants and others will get settlement from a different fund. Lawyers will also be paid from another fund. So under your scenario if only two producers remain in the suit and follow through then yes I think they will receive the entire amount. I will be one of them and I pledge here and now that I will buy all NATer's the best steak dinner you've ever had once the check clears the bank!
I was a lead Plaintiff in Starlink so some of this is familiar to me. Additionally, the attorney I've retained has been very good with keeping his clients up to date.