You are quickly finding out that the actual foreclosures aren't a big deal. Overall, the processes were fine. The documentation chain can be re-created and a small portion of loans are being rejected. Most of those can and will be refiled.
The idea that people deserve modifications is bullshit. It's not like these people can't find shelter.
As far as the Rep&Warrant issue, it's going to be a massive legal slog for anybody trying to prove it. Most documentation has some outs and even if they don't, you're going to only be able to claim those loans that are outside of the stratifications disclosed *AND* failed as a direct result of such failure to disclose. Thus, the claim is actually not $47bn (which was face amount of bonds) but rather the % of non-disclosed * % of defaulted * principal loss on the house * settlement.
Thus, lets say that you own $47bn in bonds and find that 20% of the pool wasn't disclosed. Lets say that there was 10% OC in the pool, thus the entire pool of loans was $54bn. Of the 20%, lets say you suffer 50% defaults and 50% severity, thus you only suffer 25% net losses. That means that less than 5% of the entire pool can be rejected due to non-disclosure. Now, the bank is going to argue that not all of the 20%*50%*50% was due to non-disclosure, and they'll win some of that, so the net amount may be 50% of that, or 2% of the entire pool. They'll settle for 50% of that.
That's even if you get that far, it won't. The monolines have tried and failed thus far.