This main event = a way to make HHH look very dominant. That's it.
Book him to go over against the biggest guy in the WWE, cleanly. If he flat out destroys him on top of it, and since its Summerslam, all this match accomplishes is that for the type of fan that follows exactly what the WWE tells them to do (laughs at Hornswoggle, boos every heel, etc), they'll just think HHH is amazing.
Boring. I can't see how this should be the main event. HHH has become stagnant and Khali was not entertaining in the first place. Lol. Still, it sort of makes sense, instead of having HHH just plow easily through someone like MVP/Kennedy/Hardy.
That's good, because it isn't the main event? There is Hell in a Cell on the Smackdown side and the WWE championship match on the RAW side, which will probably end up being a five way match or something. Hell in a Cell will likely be the Main Event.