I don't believe that City have seriously breached the rules and certainly not to a worse extent than many other clubs would be found to have done if they were subjected to the same level of scrutiny as we have been. I have much less confidence in the EPL judicial procedures. So in the first instance I would expect an appeal. If that appeal were rejected and our legal advisors thought that it was still a perverse judgement not supported by the evidence then I would expect that a way could be found to take the matter to the civil courts. If no way to do that could be found or if that failed I imagine CFG would have a plan B.
Probably they would plan to rebuild from whatever division they found themselves in, maybe with a notional change in ownership. If in the Championship then I imagine they would be back quite quickly.
If they found themselves in a worse position than that then I wonder if CFG would transfer their centre of operations elsewhere whilst they rebuilt City.. Perhaps Girona, some favourable transfers with buy back clauses could preserve the nucleus of a new squad. Meantime La Liga would perhaps outshine the EPL in terms of sponsorship and TV deals as it became more competitive.
In any event I think that City would come back, perhaps even stronger, within four or five years.