Yes, you'd have got away with it for a bit.
If capacity became an issue with more routes retained, Mayfield would have been available to take some of the pressure off Piccadilly. Local services from the Styal and Stockport lines could have gone there.
It really depends on the frequency. If it had just been one express and one stopper then there would have been sufficient capacity until well into the 2000s, by which point Mayfield was derelict. Had the capacity been needed before its closure to freight then Mayfield would have been a decent option (and cheaper than Central). The Hazel Grove chord could probably have been avoided for a while with Midland services running via Reddish but it would have likely been built earlier due to a better business case. I like Central as a piece of architecture and am glad the building was saved but as railway infrastructure it was never going to survive nationalisation. It was a terminal station serving a limited number of routes and close to a through station connected to the same lines.