I am not a conspiracy theorist, but let's face it, diesel is in the public eye these days. Our current government would love to do away with it completely. If they somehow create an environment artificially that keeps fuel prices high, perhaps it will give the industry more incentive to start moving away from diesel. At least, that's the plan. And it seems to be working, with Cummins developing a gasoline version of their popular 6.7L engine, Ford dropping two new gas engines in the last 24 months, and semi-truck manufacturers showing off hydrogen fuel cell and electric options to fleets. I would say it's only a matter of time until ag equipment follows suit.
I would like to note that I do not personally agree with the way things are going. I'm just pointing out how it is. This current administration sees environmental issues as their key to staying in power. All they have to do is convince folks there is a problem, and then present themselves as the solution to that problem.