Talks are ongoing, and we don't know what villain Bacon will be. Loglines for the film have hinted about a threat to all mutantkind. I'm half hoping that Vaughn, Goldman, and Bryan Singer will go really old school and introduce a member or two the Hellfire Club. Since we have Emma Frost kicking around, I'm crossing my fingers that's what's happening, and that we'll see Bacon as Mastermind. He would be a damn good Jason Wyngarde, and just the kind of mean-but-charismatic guy who could try and convince young X-Men to join him. Since Mastermind and Magneto eventually united in the Brotherhood of Evil Mutants, we would also see some sparks (and probably fatal betrayals) between Bacon and Michael Fassbender.
As I said, the good casting makes me optimistic for this film. There are a lot of great people signing on, and I'm trying not to let a love of slavish continuity poison me when it comes to the story. This has potential. Let's hope it lives up to it!