No. It wouldn't take an economic collapse.
You are pretty silly.
People who had voted for Senator Obama in the past are either going to vote for President Obama THIS time or they are going to choose NOT to do that.
He will keep his core -- more or less.
He is going to lose a LOT of the "others" who voted for the novelty of a historic first and his clearly empty promises.
YOU can "count" on some states. NY, sadly, being one.
But there are other states which it is rash to assume will go into the Dim win column and there are several "swing" states that are less likely to vote for the President than you imagine.
President Obama is going to win re-election in EXACTLY the same fashion as Jimmy Carter won reelection.