You are on to something here. When a dog has no job they get soft and lethargic much like us humans do. The Doberman is yet another example of a fine working breed that went by the wayside in the USA where looks is preferred to performance and true temperament. I remember discussing this phenomenon on here before but most of the kennel clubs do their breeds a great disservice. They talk about "preserving", "protecting" but I think the only thing the preserve or protect is their bank account.
Donovan Pinscher and Canis Panther - could be bred into a good doby line to get some strength and drive back. That is a big task as the breeder will be fighting the breed clubs and KC all the way.