If I remember correctly, MS only admitted to the RROD problem 18 months after launch when it became obvious to everyone that the failure rate was well over the 3% - 5% threshold. Like any business they weighed the cost of losing a class action lawsuit against extending the warranty to 3 years. I am sure MS went through the same thought process when they decided to extend the warranty for the E74 of death problem.
I doubt Sony will extend the warranty for the YLOD unless the problem is greater than 5%. Although it is a known problem, it doesn't look like it has crossed the threshold.