Spoilers from the Alias magazine. Typed by ciao15 at TWOP.
1) Nadia is going to live with Sydney as her roommate.
2) Jesse Alexander is going to write the third episode.
3) Season 4 is going to be about Sydney becoming her own person, separating from her father, with Nadia as the catalyst.
4) Sydney and Vaughn are going to resume their courtship and getting to know one another again.
5) They're going to deal with Irina's increased significance in a very specific way that will affect Sydney, Nadia, Jack, and Sloane the most when they learn what she's been doing.
6) The way they're going to tell stories will facilitate the introduction of more guest stars and allow the show to incorporate them into the episode in a way they weren't before (example is the Ricky Gervais episode). They would like to bring back Vivica Fox, Richard Roundtree and Quentin Tarratino. Right now, because of her availability, if they get Isabella Rossellini back, it will probably be towards the end of the season.
7) There might be some value in Lauren coming back at some point in S4.
8) What Sloane and Nadia find while looking for the Sphere of Life is going to be kept about 60% mysterious. They're going to tell some Rambaldi stories, but not as much as in the past, and there's not going to be one over-arching villain or group this year. We're going to learn something more about The Covenant that will develop over the year, while some stories are going to be a bit more contained. We're also going to meet a lot of new characters and new groups in S4.
1) Nadia is going to live with Sydney as her roommate.
I [Jesse Alexander] think with Nadia being a spy, and becoming part of Sydney's team, and being someone that is at home, means they can really develop a good relationship. As the new family relationship on the show is going to be Sloane and his daughter, and it's going to be challenging for Sydney who essentially hates Sloane – her roommate is this guy's daughter! It's going to be very challenging for her to balance her emotions, and be mature about it, and it's going to be tough for her to see Nadia interacting with Sloane.
2) Jesse Alexander is going to write the third episode.
3) Season 4 is going to be about Sydney becoming her own person, separating from her father, with Nadia as the catalyst.
4) Sydney and Vaughn are going to resume their courtship and getting to know one another again.
But they are going to have the realization that as they've both been through so much – they're not how they used to be. They're going to continue what they started at the end of S3. The fans of the relationship will be very happy about what happens, but they will also see as the relationship progresses, that there's a certain level of maturity to that relationship, and who these people are that they have to deal with. It's not going to be easy for them.
5) They're going to deal with Irina's increased significance in a very specific way that will affect Sydney, Nadia, Jack, and Sloane the most when they learn what she's been doing.
That is essentially what Sydney found out at the end of S3, when she found those papers – it was some information regarding her mother. It was as much to do with Irina as it was Jack's authorization of it. The one thing that the fans can hang onto about Jack is that he loves Sydney very much, and everything he does, in his mind, is for Sydney and to protect Sydney. There's not going to be some reveal that puts Jack in a negative light, but it will definitely complicate the way people look at him, and certainly the way Sydney thinks about him.
6) The way they're going to tell stories will facilitate the introduction of more guest stars and allow the show to incorporate them into the episode in a way they weren't before (example is the Ricky Gervais episode). They would like to bring back Vivica Fox, Richard Roundtree and Quentin Tarratino. Right now, because of her availability, if they get Isabella Rossellini back, it will probably be towards the end of the season.
7) There might be some value in Lauren coming back at some point in S4.
8) What Sloane and Nadia find while looking for the Sphere of Life is going to be kept about 60% mysterious. They're going to tell some Rambaldi stories, but not as much as in the past, and there's not going to be one over-arching villain or group this year. We're going to learn something more about The Covenant that will develop over the year, while some stories are going to be a bit more contained. We're also going to meet a lot of new characters and new groups in S4.