Don't forget Super Skrull!
Underminer Mole Man and Puppet Master might be in this too since they haven't officially confirmed who Paul Walter Hauser and John Malkovich are playing yet.
Annihilus is probably a given for a future FF movie but he's pretty much the last major one that I can think of.
As for Doom, he's one of the few villains where you pretty much expect repetition. He's so inherently connected to the FF that you just kind of accept that he's going to be there all the time, like Magneto being in every X-Men movie. And even though he's not the main villain in this, we all know Robert Doomey Jr. is due for a cameo.