Federal Reserve Chairman Alan Greenspan has been one of the most persistent advocates for shrinking Fannie Mae and Freddie Mac, but his retirement early next year may not bring any relief to advocates of a kinder, gentler approach to the beleaguered government-sponsored enterprises. Greenspan’s successor, Ben Bernanke, appears to be following in his GSE-bashing footsteps. In written responses to questions raised at his Senate confirmation hearing, Bernanke said “capping the size of the GSE portfolios,…