Ok 2 things.
1) Don't extrapolate what VW did onto other manufacturers.
2) the EPA does not set the rules for the world. Diesel will remain popular in remote areas and lesser developed nations.
he has a point about thermal efficiency, gas engines are in the 25 to 30% range, most diesels are up at 40%. If you want to reduce NOx you can use cooled EGR for a 3-5% trade in efficiency...
Find the balance though, too lean and you get a ton of NOx, too rich and you get black belches.
From what I understand there is still a long way to go with diesel exhaust aftertreatments.
diesels are once again gaining interest from the aviation industry, which is interesting on its own.