“Minus the tax advantage I think the sole rational reason for a diesel is fuel availability in geographic areas where GA has yet to develop”
And half the fuel infrastructure costs for airports who do not have to d!ck around with two different fuel supply systems.
In areas with developed GA infrastructure, there are many airports with AVGAS only, no jet fuel pumps. Many more than the converse. Those airports would be equally reticent to maintain extra infrastructure for an alternate fuel – which was the reason 80/87 was phased out.
Silvaire, GA is declining fast in the US, too. The thunderstorm is further away from where you’re sitting but it is approaching as well… 
In Europe, business/commercial GA is 99.9% turbine and in the US it is coming close to that number, too. There are airports that rarely service recreational GA and for those, AVGAS is not a business. It my home airfield, we have 3 types of fuel (100LL, Mogas, Jet A-1) and AVGAS is the #1 seller by far because it’s mostly recreational GA.
At my base, we have two competing suppliers of AVGAS and Jet-A, and you can get either off the truck at your hangar. You can also get AVGAS at a slight discount by taxiing to the self-serve fuel island. So no problem regardless of what you’re flying.
However, at smaller airports it’s more often self-serve AVGAS only, because nobody flies a jet into a 2000 ft/600 m paved runway at a unattended airport, and the helicopter business wouldn’t justify an extra pump. I think if you had a diesel you wouldn’t have any insurmountable problems, but you’d need to plan on fuel stops at larger airports instead of assuming that you can top off the tanks anywhere along the way, without planning. Turbines are not a big fraction of the fuel business at most airports.
