I agree, I don't think HydroPhi is going to be able to sell the HydroPlant as a stand alone. However, I can see the tech being either sold or licensed to an engine manufacturer to integrate into a new engine.
The major issue with the diesel engine is not the normal green house gases that we think of (CO2), but are gases resulting from the fuel & oxygen combining with Nitrogen(NO2). Tech is hitting the point that the only way to reduce NO2 emission is to reduce the amount of outside air required for combustion. That is where HydroPhi's tech comes in. By dumping not only Hydrogen into the combustion, but also Oxygen, that means the engine does not have to draw in as much air from the outside; therefore, less Nitrogen is available to form NO2 and any other Nitrogen related pollutants.