If we really sign Howard I don't see why we should keep both Millsap and Horford.
Sure, we would have top Nba combination at the 4-5 sports for all 48 minutes, but we would still have a SF black hole.
'Sap can maybe play the 3, but for few minutes and not at his actual potential. And Splitter would be useless.
If we really sign Howard, we need a (sign and?) trade.