Doc Ock has to be the leader of the team. The team is essentially his baby.
Also, I don't believe it will be a rehash. I liked Doc Ock in SM2 but they made him a lot more sympathetic than the Ock in the comics. The Doc Ock from the comics is arguably the most egotistical villain on Spider-Man's rogues gallery, despite what Dan Slott might want you to think. He is an evil genius and takes pride in it. He wants the whole world to know that he is the one behind a terrible scheme at hand whenever he causes one. I would love to see that take on Otto on the big screen. On top of that, the S6 won't be showing up till TASM 4 at the earliest assuming they're smart, don't rush things, and play their cards right (though I personally think they won't show up only after TASM 4). That is in 2018 or after. In other words, a minimum of 14 years between Alfred Molina's Ock and the new Ock.
Also, it would be nice to see a good Doc Ock on the big screen since Slott is completely butchering him in the comics at this point (along with Spidey himself).