Your average person couldn't tell you the difference between a diesel and a gas vehicle, especially the younger population. Change is incredibly slow. A good start would be emission inspections and certifications across the board, its not even remotely close to that. Our diesels (whatever ones are left) in 20 years will still be chugging along same as today. What may make them impractical is getting "only" 25mpg when diesel costs $7+ a gallon.

I am enjoying modern tech. The direct injection gas and direct injection diesel in my newer vehicles are leagues ahead of the old tech. More complex, sure, but plenty reliable, and great performance/economy. I was cruising around for hours in my GLK today at 80+ getting over 34mpg....in quiet comfort. Well worth it.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

as much as I love our old diesels I have to agree with everything you said. I have several indirect diesels of almost every brand, and none can compare to the common rail that I have in my pickup. It currently has 500000 miles an unknown hours as the hour meter pegged out at 10,000 years ago on about $2,500 worth of repairs. That was injectors and lift pump at 330,000 approximately