I guess, I figured out why Barak did it and what is it that Netaniyahu promised. Netaniyahu needs Barak inside Likud - and that's where it is going. Firstly, Netaniyahu, however sad it sounds, is left of center within his own party: like any party leader he'd prefer to be in the center. Secondly, Barak can strut around in his uniform and medals - Netaniyahu is a relative civilian (to the extent there Israeli civilians at all out there), he needs somebody to cover for him in that dimension.
So, Barak and, probably, Vilnai (also a general), are going to get a couple of places reasonably high up on the Likud list - Netaniyahu will see to that. These two might also be used to attract some of the old Labor Ashkenazic elite.
The other three, I am afraid, have just bought some really sour lemons. Though, Simhon and Noked might be used to attract some of the moshavim and kibbutzim dwellers - rural rightwing commies, for god's sake
)! Still, I have a strong doubt they'd get anything like a realistic spot on any Likud list in the forseeble future.