If this (GM) and Dodge emissions defeat turns out to be true, the question would be "why"
If the current emissions laws are unattainable then it is likely Ford, isuzu, etc are in this too. It is unlikely that the other big players are meeting the epa regulations and GM and Dodge cant figure out how and had to figure out how to "trick" the test.
So, if all the others are also doing the same then there is going to be some big changes coming. It is possible that they may relax the regulations but it is more likely that everything will get a lot worse. We may see the big three pull out of the diesel market all together. The only on road diesels will be the big rigs (maybe) and the trucks already on the road that dont get recalled and crushed
I am betting this is just a couple of wackos jumping on the bandwagon trying to get a payout