It's funny how things go.
Up until about the mid-late 1990s, three at the back was used in nearly every country, even England, though perhaps not quite so much here.
I remember Kendall used it at City for a while when he first came here.
Then everybody seemed to decide that a flat back four was the way forward and the sweeper system has hardly been seen since.
I think it could work for City, especially if the three are Vinnie, Micah and Joleon, with VK as the libero. We all know that Zaba, Clichy and AK have the engines to play as wing backs and I reckon Jimmy could too, if necessary.
I think it's an option that Bobby Manc should seriously consider.