They are going to be faced with a massive number of completely useless batteries filled with toxic chemicals. Old batteries have been around for some time obviously, but not in this kind of numbers.
They’ll be safely recycled and disposed of, I’m sure, but the time and effort (and money) it will take to do so will surely be unprecedented. I’d be a little nervous, too, about transporting and storing all of these little potential fireballs before they got recycled: nothing ruins your day when you’re the pilot of a cargo plane more than a minor explosion.
I’m not saying I doubt Sony’s ability, and I’m certainly not saying I feel sorry for them. It is just an interesting side note to this battery mess.