By Michael Ide, Staff Writer at ValueWalk: Falling fee income, tough regulations, and shareholder pressure could make diversified banks spin-off their retail banking units, argues The Edge Consulting Group. Regulators worried about the size and complexity of banks that are too big to fail might get a market solution to their problems, at least according to The Edge Consulting Group, which expects diversified banks to start spinning off their commercial banking divisions in the next few years as the best way to increase shareholder value. Three specific banks to keep an eye on are Deutsche Bank, HSBC Holdings plc (ADR) (NYSE:HSBC) (LON:HSBA) , and UBS AG (NYSE:UBS). Diversified banks to watch for a possible spin-off are…