This isn't a comment on Eagles v Cowboys in future but the Kelly offense
I think it can work. The NFL evolves. Look at Russell Wilson and Colin K. No one thought a decade or so ago that upwards of 10 QBs would get close to 5000 yards. People are still talking like hurry up offenses are "gimmicky" when in all actuality they are becoming more of a norm. It won't be right away but offenses are finding better ways to attack defenses that got bigger and stronger. We've seen a transition from 1 main RB getting 20-25 carries to RBBC. I definitely can see a time when offenses go to something like Kelly runs. Defenses will catch up. And then we will see another trend. Its the evolution of the league. Especially now with the new DB rules and non-intimidating hits allowed on WRs.