I think we will see liquid fuels from biomass to continue using legacy equipment, trucks, etc. There is a Canadian company making liquid fuels from cellulose, specifically as a replacement for diesel and heating oil. Should all be fairly clean with the only emissions being carbon, water, and NOX. Good filtration and carbon capture tech will make these fuels carbon neutral. Porsche is also working on liquid biofuels. These same fuels should work well with internal combustion powered OPE.
My tractor is indeed a tier IV with DPF, 45hp. I'd like to get the ECU tuned to the 60hp mapping, but that will be some time down the road. My truck is one of the last years without DPF, I think they came in 07 with the 6.7 Cummins.