How long can it last? Even though the economy is jumping, unemployment and inflation are low and the Dow is at a record high, Americans remain pessimists. The Conference Board's index of consumer confidence dropped to 126.5 in July, down from 129.9 in June and well below the 130 that Wall Street analysts had predicted. Sure, consumers said they feel great about the state of the economy right now. It's the future they're worried about. Everybody from the federal government to the fully invested cabdriver is laying plans for the downturn, or even the crash they fear is coming. But not quite yet: encouraged by today's report of an unalarming 0.8 percent rise in wages and benefits for the April-June quarter, the Dow was up another 53.42 points for a new record close of 8174.53.