FOUR years ago this August, a Republican Congress pushed a reluctant President Clinton to sign a bill that ended welfare as we had known it. But since the 1996 welfare-reform act expires on September 30, 2002, its eventual fate is not yet clear. Much will depend on how the law’s impact is viewed. So far, it certainly seems to be a success. By June 1999, welfare rolls had fallen an amazing 49 percent from their historic high of five million families in March 1994. That’s nearly seven and a half million fewer parents and children on welfare.