I can imagine this happening: Delaware's requirements are strict enough, and we don't issue non-resident permits.
When I read HB52, I could see it was doomed: it called for Maryland to recognize permits from three states with widely varying training and other criteria, and it didn't exclude non-resident permits. It would have allowed MD residents to carry with a VA permit. That law wouldn't even have passed in Delaware.
Reciprocity with Delaware, on the other hand, doesn't enable a single additional MD resident to carry. The AG's can make such a deal without legislative action.