Obama's chance of winning reelection in 2012 would have greatly been diminished, if not totally compromised (unless, of course the Republicans ran Trump, Palin or Bachmann) should he have chosen the most risky option he was given over the safer ones and the mission failed. He would have been hammered into the ground by the Republicans the rest of the campaign season and throughout history. Can't you hear it? Reckless. Made his decision in a vacuum against the advice of those whose expertise were far superior to his own.
Beyond that and back to your question, almost anything could have happened. Here is a link to the rescue mission Jimmy Carter attempted when 52 Americans were being held by Iran:
http://en.wikipedia.org/wiki/Operation_Eagle_ClawCarter himself blamed the failure of this mission as a largely contributing factor to his failure to win re-election.
In my opinion, both Presidents were heroic for attempting these missions. It is just that one of them learned from the mistakes of the other, and he also had the benefit of more time to plan the details. In doing so and in conjunction with his military advisers, he left no stone unturned. Still, President Obama could have experienced an unexpected snafu, the mission might not have been successful, and he would have faced an even greater amount of criticism for invading the borders of a sovereign nation.
Bill Clinton and George Bush both were given options such as the one President Obama was given, but only President Obama had the raw courage and nerve to bet the farm. This is one of the salient reasons he has been repeatedly called gutsy by those on the inside since he dared to do what both Clinton and Bush declined to do.
It is very seldom one observes a politician take a risk which might cause the future loss of an important election. This is exactly what President Obama did, putting the best interests of this Country over and above his own political welfare, and that alone makes him truly deserving to be called The Commander-in-Chief.