Let's ignore the question of whether or not the Patriots actually did anything and ask this hypothetical question:
Assume that a team made an intentional effort to change the pressure in footballs after they have been checked. (I'm not sure why people are assuming that would have to mean someone sneaked in with a needle to tamper with each ball individually and not something like trading one sack of balls for another.) What should be the penalty?
Ideally, your answer should be the same as it would be if Ballghazi had never come up, but let's be honest, that's not going to be true for everyone.