Suppose it is 2011 and the Volcker Act has recently passed, sharply curtailing U.S. banks' riskier activities and separating them from retail deposits. Citi's recently arrived chief executive Bob Steel, who is dismantling the group, puts out a memo to the bank's staff saying Tim Geithner has been hired as head of the bank's strategy and investor relations. Oddly, the imaginary scenario is not such a stretch.