I also think people who lament what might have been had Jerry and Jimmy been able to keep their egos in check miss some other realities in the process.
One, right or wrong, Jimmy is simply not a happily ever after guy as a football coach. That is a key part of why he didn't last that long in Miami too IMO. He had other aspirations, goals and ideas. The ego clash with Jerry was simply the eject button that was going to happen really soon in Dallas no matter what IMO.
There are also reports that Jimmy's fear/intimidation approach had grown very tiresome with some. Not all of course. And probably not the triplets in particular. But then I think we already discovered they could not do this by themselves either.
I think its quite possible that had Jimmy stayed we might have not fallen short in 94, and still won again in 95 as we did under Barry. But I think the ride would have ended there even with Jimmy on board. Age, injuries, some players getting out of control due to success etc.
IMO, age, injury, self-destruction (Lett, Irvin, Erik?) free agency, the cap, lower draft slots, & fewer picks, all played bigger roles in our ultimate decline than Barry being less prepared than Jimmy, or Jimmy's departure from the war room (which is not at all to make excuses for Jerry/Larry's pitiful drafts).
All the above are why dynasties are so rare.