They won't openly endorse Hillary, because to do so would be to admit that the "choice" between Democratic and Republican establishments is no choice at all. It's important to maintain the charade that there's a real ideological divide between the Clinton-type Democrats and Bush Republicans, when they are really one and the same.
As I said earlier, the Bushes and their political team (Rove, the neoconservatives, etc) will help Clinton by pulling whatever strings they can to sabotage Trump in the general election. They'll just do it behind the scenes.
You always have a choice; you can vote for a REPUBLICRAT or a DEMICAN.
Personally, I think I will go TRUMP.