I think Legacy could have been so much better had it not been used as a prop in the Orton vs Triple H saga. Like many people have said, Legacy could have been the new Evolution, maybe not in terms of having an veteran, a monster, one for the future and the present "man" so to speak, but in terms of being the next big (and popular) stable. We are still feeling the effects of Evolution and it's demise a number of years later and I think it would have been good if Legacy could have had the same effect, there is still time for this to happen, however I just think Legacy has missed its opportunity to be bigger than Evolution.
Saying that, I would rather Legacy stick together as a 3 man unit (even though I would rather have Priceless dis-align themselves from Orton) than add another member, especially DH Smith.
I like the Mr Kennedy idea and some people thought your scenario would take place at WrestleMania however I think this would make this storyline even more complicated than it already is and would mean this storyline would carry on for another couple of months which is not a good idea seeing as it is already drawn out.
Don't know why DiBiase is rumoured to be turning face and I don't think he should, it's too early.