What is Your Story's "What If" Factor?

I began writing “Alien Line” in 2007 now as year 2010 comes to a close it is complete.  Since declaring the manuscript done some months ago I have started this blog, done extensive research on how to write a query letter, on how to acquire an agent, on why writing conferences are important, on how to deal with rejection and read through numerous content posted on other writing blogs.  Great right?  In a way yes.  I must admit that this journey has helped me to hone my craft, something that is essential for a serious writer.  But still there are moments when I wish I could slip on a pair of glittering heels that would enable me to go back in time.  Back to year 2007 when I was staring at the dreadful blank page poised ready to type that first line.  I would tap that slightly younger me on the shoulder and relay as much of what I have learned about BANKABLE fiction as I could before those glittering heels pulled me back to the present.
And I would tell her to consider if the story idea is of the HIGH CONCEPT kind.  Meaning is this an interesting, simply understood idea that can be explained in a mere sentence or two?  I would even be so kind as to give her, me, whatever an example.
Resting after a long labor Sylvia wakes anxious to see her twin girls only to have her husband and doctor insist that she had been pregnant with only one baby. 
Easy to follow right?  And such a concept or pitch leads to a what if or why did type of question.  What if there was another baby?  Why did the husband and doctor lie to Sylvia?  As the glittering heels lit up, signaling that it was time for me to go, I would offer one last bit of wisdom: this is your baby but it will be someone else's product.  Write the story you have intended to write yet when the time comes know how to pitch this story.  Know your story’s what if factor.