While it's true that Sony hasn't given a definite promise for when PSN will be back up, I don't think "indefinitely" gives an accurate impression — they're still saying that they're trying to get back online as soon as possible. So there's really nothing new in this article (and it's self-blogspam as well).
So does this lend credence to the theory that the attackers compromised the network to the point that they were able to install compromised firmware on users machines?
If they didn't I imagine that Sony is afraid that they could have. I'm more curious if credit card numbers etc. were stolen...