I agree with you in general. I think over time fields that are "fuzzy" with definitions, like psychology, will hopefully add additional layers of specificity to a number of neuro diseases/ailments/conditions. In the end if you took any condition out of the DSM each human probably falls some where along a spectrum for each one and the ultimate combination is what makes us "us" as individuals.

I could certainly see autism be rated on a 1-10 scale of severity to provide additional clarity or each one of those ten points on the gradient receiving a new diagnostic name. Going further we could probably have a broader scale that includes severe autism on one side and severe empathy on the other. The empathetic traits aren't as well studied even though being severely empathetic can also have a host of social challenges.