The entire diesel industry is waiting for the 2015/2016 mark to come and go, for the US Tier 4 / Euro 6 emission standards, which is going to be a huge change in things. As of right now, it's much easier to build a diesel to fit Euro standards, then the US standards. Come Euro 6 / US Tier 4, that actually 'flips' a bit, where it will be easier to build a diesel to fit US emission specifications.
Rumor is right now, to follow up with the Jeep Grand Cherokee's diesel, the Jeep Wrangler will be getting a 2.8L VM diesel for the 2014 Model year or at the latest, the 2015 model year. As of right now, Jeep brand cannot pass CAFE standards for mileage, mostly due to the wrangler - getting the top end of 19 MPG, where as a fleet needs to average 36? I think, in 2016. Jeep doesn't have that many ultra-fuel efficient cars to balance things out either and the 2.8L diesel is already proven in Europe to get equivalent of 30+ MPG. So even with new emissions stuck on it, you're looking mid to high 20's.
Ford's project 'Lion' has recently become reactivated in the US, after being put on pause since 2003/2004. This is a 4.7L twin turbo diesel, much of the same breed as the 6.4L V8 powerstroke that was seen in the 08-10 model years. As a lot of people know, the 6.4L engine with a bit of tuning is one of the most powerful engines ever released - with the ability to break 800Hp with the stock turbo / fuel systems. However, not the most fuel efficient in the world. Project Lion though, fixes a lot of the issues that the 6.4L had, as it has been in design much longer then the 6.4L was and uses a lot of technology taken from Land Rover's diesel that have been around for ages in Europe.
The only way a 1/2 truck is going to be able to meet CAFE standards in the future is with diesel engines and within the next two years, my sources have basically said everything will be going the way of diesel or natural gas.
Bi-fuel (Gasoline/Natural gas) already 'in the wild' and every major engine manufacturer is pushing R&D funds towards natural gas engines hard, as the different shale booms in Texas, North Dakota, Ohio, PA, NY and Colorado make access to it extremely cheap.
The other nice thing about Natural gas engines, is they are currently not regulated by CAFE standards, so for auto manufacturers, it would be a nice way to increase their standings, without hurting their CAFE standards. (Natural gas engines currently fall into the same category as electric vehicles as 'alternative fuel' vehicles, and have the tax credits to meet them.)
The next 4 years in engine development is going to be really interesting. Diesel is going to be the #1 choice for fuel real soon, as they get more and more efficient and the emissions stuff gets simpler and simpler. Solid state urea is going to make the gallon jugs of it go away, using water from the exhaust or AC units to make the exhaust fluids. Plasma/Propane based systems for heavy trucks will get rid of DPF's and DEF all together, in the next 5-7 years.