This lawsuit seems pretty shady to me. Lawyers just trying to cash in on the class action biz. Heck, they don't even have enough plaintiffs, nor has a judge granted class action status to their suit.
As far as longevity goes, I have a Socket 939 Athlon 64 X2 that is still going strong. Every manufacturer has a few chips that don't pass muster including AMD, but I think if you look at the total number of these laptops shipped, it would represent a normal rate of failure.
Having said that, if this is true, then Apple should be stepping up to remedy the situation. After all it's not like AMD could send out a replacement video chip since most of the time they are soldered onto the motherboard. It would then be between AMD and Apple to sort out who would be liable to cover the cost.
(Full disclosure: I am now part of AMD's Advocate Program. I do not speak officially/ legally for them in any capacity, but I am in their corner.)