My understanding is that this type of setup would be ideal for a truck going forward with the new regulations on the horizon.
There would be high development costs, but imo they would pay off if the new drivetrain provides good performance and fuel economy.
There will be alots of things to think about for such a setup versus gas hybrids. One thought that occurred to me is instead of shutting off the internal combustion engine like gas hybrids do; maybe it would be more efficient for a diesel to instead drop into a clean idle mode, where it continues to generate power.
What is your interest level in such a vehicle?