I think that DX should consist of HHH and HBK "passing the torch" while still building credibility with existing wrestlers. For DX to work, Cena should stay on his own and help Vinnie Mac when he feels like it. Plus, Cena is gonna fued with Edge for a little while longer.
If the plan is to bring Haas back, what better way than to have him back with Benjamin. The two of them could act as the "setups" to the HHH and HBK "punchlines". Shelton's "problems" with HHH could create a stronger storyline for him later down the road, and give Haas some mic and camera time.
If "the World's Greatest Tag Team" can't pull it off, then I cant think of any other tag teams that could keep my attention. There's always the Basham Brothers or bring in Helms and Moore from Smackdown (they would be great for comic relief and use to wrestle as a Tag Team back in the day).
I don't think there would be anything wrong with Nitro and Mileena (sp) bringing another facet to the new DX. They would definitely get everyones attention everytime she ends up going to the ring.
Your Kahn-chents has spoken.