If the Supreme Court stayed out the result would be clear.
1) The state results will be contested by whichever party does not win.
2) Voting by state delegations, one vote per state, the House with 30 Republican majority delegations and 20 Democratic majority ones awards Florida to the GOP.
3) If the Senate also goes for the GOP then Bush wins. If the Senate does not, perhaps with the Democratic ticket of Gore and Leiberman casting the deciding votes, then the Constitution is clear on how the split is decided.
4) Florida Governor Jeb Bush picks the next president. Possibly he graciously steps aside and allows the Lt Governor, chair of Bush's Florida campaign, to make the decision. Or Florida Secretary of State Katherine Harris...
5) Endless articles, opinion pieces and learned tomes emerge in the future blasting the Supreme Court for the decision to not involve itself in the matter.