Of course I don't know the extent of the infractions they're being investigated for, but if you start to impose fines that are percentages of your club's worth (around 4 billion £, according to Forbes), and then you add TV rights and prize money to those fines, along with one or more seasons without new signings, then even a club as rich as City will suffer.
Obviously, a fine as ridiculous as the one UEFA imposed on PSG (65 million €, if I'm not mistaken) would make City's owners laugh.
If if you strip them of their titles you're not leveling the playing field, it looks like vengeance to me, those trophies are still gone, the other teams won't be playing those seasons again.
I disagree. Fans and players are not at fault here, unless overt corruption, match-fixing or doping is discovered I don't think fans and players should pay the price by having a club stripped of their titles, I don't like punishments with retroactive effect, or punishments that hit indiscriminately, even those who didn't do anything wrong.
If City, because they didn't follow the financial rules did have a unfair advantage, then they should be punished starting next season, huge fines - I'm talking hundreds of millions - and multiple seasons without signings, that even applies to their under 23 team, or B squad, the "Primavera" team as we call it in Italy. (I'm guessing they have one).
Punish the executives, hit the club hard both financially and technically, heck, I don't know if it's feasible but you could even force them to hand the money from stadium tickets and season tickets.