Let me try a little different spin on this.
Big Tobacco did everything that could be done to protect their business. (I actually spent some time working on one of the key cases; not my normal gig, but I had some time and I resented the government's efforts, so what the heck.) In the end, I believe tobacco lost because of public opinion. It just was not possible for the "death merchants" to get a fair trial, and the reason was that there was too much public support for the government's efforts. Trust me, judges read the papers, too. The handwriting was on the wall, and tobacco had no choice other than to fold.
Here's my point. I think, or at least I hope, that the government and the big plaintiffs' bar are on the verge of going too far. I think the public got behind the tobacco suits because: (1) almost everyone knows someone who died from cancer, (2) there's that "addictive" thing, (3) there was a sense that tobacco was doing a lot of covering-up, and (4) most people don't like cigarettes. I just don't see those factors translating to a suit against McDonalds.
This time, I think the tide of public opinion will utimately defeat the forces that want to control our lives and our choices. How many soccer moms will believe they've been "abusing" their kids for years by taking them to McDonalds?
So if I'm right (and I may not be, ask my wife), and if these lawsuits materialize and end up losing, they may actually provide us with a little breathing room for maybe 10 years. The government and the plaintiffs' bar may just back off for a while. We'll see.
By the way, don't dump the diet in the meantime. Even if these suits succeed, you'll see exactly as much money as smokers received (as compensation) and non-smokers received (as health insurance rebates) in the tobacco settlements: none.