well, Clinton got 53.41% of the two-party vote. that's an Obama 2008 victory. you can argue from there. obviously states like Montana would flip to Bush. but the takeaway story from 1992 was how poorly Bush (R) did: 37.5% as an incumbent.
counterfactuals are silly, but the conclusion has to be that Bush very likely still would have lost. even to a Massachusetts scarecrow like Tsongas.
Actually, in a no-Perot world, I think Bush is narrowly favored. Don't underestimate Perot's impact as a credible non-partisan voice hitting Bush over the head on the deficit with independent voters. And remember that 1996 and 2004 are basically automatic incumbent party wins. Without Perot in 92 or 96, it's very possible that the Republicans don't lose a presidential election again until 2008.
Bush's job approval rating was pretty miserable throughout 1992. People were pretty upset about the economy. You really think that would have been different without Perot talking about the deficit and trade?