If Obama wins by a similar or larger margin than in 2008, Orange County will likely go his way.
No.
Why not? Orange County will only become more Hispanic between 2008 and 2012, and McCain only won the county by 2.56%. Any national increase in support for Obama coupled with the increase in minorities will certainly lead to the county flipping even if only narrowly, especially if the Republicans nominate a strong social conservative like Huckabee, Santorum, or Palin who would be massacred in many suburbs. If support for Obama is at a level similar to 2008, the increased hispanicity could very well change the result. Obviously, if Obama is more unpopular in 2012 than in 2008, he will not win the OC.