If I had to guess right now, I'd guess sporting deductions, relegation, fines. I dont know what the Italian punishment is for misleading/fraudulent accounting on a club level but those are inlikely to have a sporting impact.
I dont think there was a precedent set in 06 about contractual termination, was there? Everyone I can think of off hand was sold? Revenue hit will be painful for Juve, they might lose some sponsors but doubtful as their main sponsor is self-sponsored anyway. I'd expect some important players to leave, e.g. Vlahovic. Probably some of them will stay, like Chiesa etc.
Seems that there have been pressures from Consob, the Italian entity that vigiles on Companies that are on the stock exchange, and also from the Italian Procura, the prosecutor's office.
So, during the last board meeting they discussed harshly and finally Elkann decided to remove the whole board.
They resigned but kinda forced to.
What can happen next:
For what Consob concernes, if the financial irregularities are confirmed and proven, there can be fines and even jail (depends on how intentional were these irregularities) for the former board's members.
Consequently, another trial will start for unfair and unethical conduct from the Italian Sport Court, more or less what happened in 2006 for Calciopoli, ended with their relegation.
On the other end, their are under investigation for mafia infiltration in their supporters groups and Camorra's affiliation, since Agnelli has been found repeatdly having direct relations with their members.
Bad times for them, good times for the whole football movement in Italy.
It won't matter. It's like me sharing an opinion on Trump's election. Irrelevant.
The only thing that matters as far as I can see is what the Lega decide - there may be some reshaped FFP implication as well, but that'll come from UEFA. The overarching punishment will be Serie A though.