It looks like other than GE's current line of freight locomotives and some genset types, all other current Tier 3 locomotive designs will be discontinued as of Dec 31.

There is some disagreement what EMD will do. I think they will continue to use the 710/SD70 by claiming CAT's emission credits until they rework the 265H into a compliant engine in 2017. A friend in the locomotive industry disagrees and thinks EMDs will be built using compliant Caterpillar engines. Cummins also has a new high horsepower diesel that has seen some limited applications though I am not sure any is in production. Both the Cummins and CAT engines will require DEF/Urea and I really can't see railroads eager to install and maintain DEF storage and distribution facilities at all fueling stations or limit these engines to certain territories.

Commuter engines have grown into fat pigs with all the crew comfort/collision/HEP/AC equipment being added and the insistence of having 4000 hp to accelerate from stops. Now with further emissions equipment having to be carried and around 12% of fuel tank capacity to DEF, it is just a matter of time before passenger designs have to revert to A-1-A just to carry the weight.

There is also LNG which is being resurrected, but it comes with its own fuel issues especially the fuel tenders.

Regardless - we are in for a huge change in locomotive designs as of Jan 1. And remember what happens when the emissions system isn't happy - it shuts down and pouts. Ask any medium or heavy truck driver how reliable their new "green" engines have been.