Surely it needs to be made void on the basis that every other position in the league is affected if they hand the titles over to second place?
Exactly this. Where does it end?
I made this point earlier, that the best thing to do if found guilty, is simply put a line through their wins, like the UCI did with Lance Armstrongs wins in the Tour de France.
Its easier to do with something like Pro Cycling, where it only affects the top 3 standings in a race for medals (you could simply promote the 2nd place to winner, 3rd to 2nd etc) but in the Prem, that's a lot harder to do.
It's not as easy as giving the runners up the title, because what happens to the 5th place team? The ones that should have got CL football the following season? Do they claim for compensation from City for loss of earnings?
Likewise, go to the bottom of the table and the 3rd from bottom team who got relegated, could lodge a compensation claim that they should have stayed up. It opens up a right minefield for the Premiership and City.
I'm not saying City should be let off, no way, but in terms of their wins its far easier to just put a red line through all of their achievements in the years they did cheat, if found guilty (and demotion to League 2)