Well first off, the Siege of Yorktown was in 1781 not 1776. Secondly Yorktown was a foregone conclusion once the French Navy beat the Royal Navy at the Battle of the Chesapeake. Thirdly, had the British actually won the Revolution, trying to speculate on what result a vote in 2010 without some idea of what had happened in intervening 23 decades would be pointless. So you'll have to wait for gporter to discuss this with maps.
Indeed. If the British had won the Revolution, we'd be looking at an entirely different world complete with entirely different geopolitics, demographics, and politics.