It would provide great entertainment, but guarantee Obama's re-election. Not worth it, IMHO.
I don’t think it would guarantee Obama’s re-election. We have a perfect storm for a third party candidate this year. At least half of the Republican voters would go for Sarah if they thought she was a viable candidate.
The Reagan Democrats and libertarian leaning democrats would also join in supporting her. There are enough anti-establishment, anti-big government and anti-corruption people in both parties that I think she would win. Rural america could win if Obama and Romney split up the cities. Romney can have Utah and Nevada.