Fa sha the market is demanding diesels, not sure if the EPA is going to allow it in the near future. But with the current slash and burn administration...even the future of the EPA is in question. Which is a mixed bag for me...would love fuel efficient cheap diesel (which doesn't exist)...but don't want polluted air and water either.
I think North American car companies and engine makers are planning for the worst and hoping for the best; they're future engine designs will likely continue to incorporate and improve upon emissions technology because they know that over the long-term that is where the North American and global markets and regulations are heading towards. If you go read up on some of the current domestic offerings, you'll see that North American diesel engine manufacturers, by-and-large, have been successful at making diesels emissions-compliant while still maintaining some measure of fuel economy and reliability.
Also, I don't think the EPA is going anywhere, despite the predictions of some media outlets.