Nothing, this is one thing that came to my mind this morning, or: How would life be if Ben was perfect. Obviously he would be with Juliet, she would counter his love and a person would find it interesting, intense, loving and cute (?). They would have three children, twins (a boy and a girl) and an older son named after his grandfather ... John XD
John Locke then it would be a sort of "Grandfather Locke," the gentle grandfather who tells stories to little ones the magical island and that occasionally leads them in person to collect tasty fruits or follow in the footsteps of wild boars (when they are older , teach them to hunt really).
If the life of Benjamin Linus was perfect, her daughter did not hate him and would not be engaged to Karla, but with a nicer guy, more awake, which also likes to Ben and that looks also to Richard, being the nephew XD (But do not I illustrated this part, it seemed unnecessary ...).
If your life was perfect, also, Jacob would keep into account and the Island would never allow one to take a tumor in the spine.
And so it would be a great life, happy, full of adventure and twists (because the island is just so) and to overcome adversity all together ...
But of course, this will always remain just a dream. The strange, impossible, dream of Benjamin Linus.