The Mad Men season finale left a real easy way to get rid of a whole bunch of cast members. So, who is going to leave this critically-acclaimed show for fame and fortune and who is here to stay?

While Mad Men is a critical darling and its ratings are growing, it has never been a ratings bonanza for AMC and the pay is notoriously low. And after three seasons of being on "TV's best show," the siren song of more lucrative TV and movie roles may be irresistible. Plus, the way that series creator Matthew Weiner left things — Sterling Cooper as we knew it is dissolved, newly formed Sterling Cooper Draper Price may make it out of the Pierre Hotel, and Don's marriage is effectively over — almost any any character could be easily written out. So it would not be surprising if some of the regular characters disappear entirely from the show by next summer with nothing but a line of dialogue — "Oh, Peggy couldn't stand working next to Pete and Duck hired her after three weeks" — and a guest appearance or two.

Here your betting guide for who's coming back as a regular for Mad Men's fourth series, from most likely to call-your-agent.

Don Draper
 Played By: Jon Hamm
Last We Saw Him: Lording over his new kingdom in a hotel room.
Why Stay: There wouldn't be a show without him.
Why Leave: After a great guest spot on 30 Rock, Hamm is getting more attention than anyone in the cast, for drama as well as comedy. He's also involved in several upcoming movies like Howl, The Town, and Sucker Punch.
Odds of Returning: 1: 1,000,000 (come on, there's no Mad Men without Don Draper)

Peggy Olsen
 Played By: Elizabeth Moss
Last We Saw Her: Working for Don at the new firm.
Why Stay: She's a fan favorite with a great role and her character is on solid ground at the new firm.
Why Leave: To be a movie star! She's come a long way since her days on The West Wing. Between this an a well-regarded turn on Broadway opposite sushi-poisoned Jeremy Piven in Speed The Plow, now may be her time.
Odds of Returning: 1: 500

Roger Sterling
 Played By: John Slattery
Last We Saw Him: Don's new best friend and business partner.
Why Stay: Roger gets all the ladies, funny lines, and best bits. Who doesn't want to play the scene stealer. Plus, Slattery and Hamm are besties.
Why Leave: There will be plenty of work for a veteran character actor like Slattery—work that probably pays a lot better.
Odds of Returning: 1:200

Pete Campbell
 Played By: Vincent Kartheiser
Last We Saw Him: Don's new protege at the new firm.
Why Stay: He has a nice juicy, high-profile role that's far better than anything else he'll land.
Why Leave: He doesn't have a good reason.
Odds of Returning: 1: 100

Joan Holloway
 Played By: Christina Hendricks
Last We Saw Her: The new office queen of Sterling Cooper Draper Price.
Why Stay: Because if she doesn't, we will slit our wrists.
Why Leave: Holloway is a sexy lady who has been on the fringes of TV for awhile. She may see this as her break. She's in next winter movie Life as We Know It, and she has proven to have the looks and the talent to anchor a TV show of her own.
Odds of Returning: 1: 75

Trudy Campbell
 Played By: Alison Brie
Last We Saw Him: Delivering a cake in a wonderful red bucket hat.
Why Stay: Who else is going to nudge Pete in the right direction. And we need someone to show off retro fashions.
Why Leave: This isn't the biggest role, unless she and Pete get an upgrade.
Odds of Returning: 1:50

Harry Crane
 Played By: Rich Sommer
Last We Saw Her: Eating one of Trudy's sandwiches at Sterling Cooper Draper Price.
Why Stay: He was saved by this plot twist, which means the writers have something in store for him.
Why Leave: Harry never gets to do much of anything, not even supporting character zany. He may want to stretch his legs.
Odds of Returning: 1: 10

Betty Draper
 Played By: January Jones
Last We Saw Her: On the plane to Reno to get a divorce from Don with her future ex-husband Henry.
Why Stay: Because it would be great fun to watch Betty get tortured some more.
Why Leave: She has every reason to leave. Betty's storyline is at an obvious stopping point, at least as featured character. January Jones has been making the PR push, putting her boobs on GQ, hosting Saturday Night Live, and attaching herself to a number of projects. She also has a part in the upcoming Pirate Radio, so it certainly looks like she's planning a busy schedule away from Mad Men
 Odds of Returning: 1:5

Sally, Bobby, and Gene Draper
 Played By: Kiernan Shipka, Jared Gilmore, some baby
Last We Saw Them: On the couch with Carla being dazed by the TV.
Why Stay: They're kids. What, would they rather go to like real school? Also, they're Don's kids. You can't just erase them.
Why Leave: Or can you? If Betty leaves for good (maybe she and Henry settle in Reno and open a casino?) the kids go with her. And Bachelor Don is going to have plenty of babes to play with.
Odds of Returning: 3:1

Ken Cosgrove
 Played By: Aaron Staton
Last We Saw Him: Left at the former Sterling Cooper, but as head of accounts.
Why Stay: A steady job—albeit a small part and, hey, maybe the writers need a way to a character to demonstrate life inside soulless McCann-Erickson.
Why Leave: Staton would be bummed to be cut, but it'd be really easy for him to go off and finally become a novelist.
Odds of Returning: 5:1

Bert Cooper
 Played By: Robert Morse
Last We Saw Him: Keeping the sofa warm at his newest ad agency.
Why Stay: As an older gentleman, just like Cooper, if Morse leaves, there isn't going to be much work for him elsewhere. At least not with this high a profile.
Why Leave: He may not have a choice. Cooper doesn't do all that much, and when they need a big shock, it will be easy to give him a stroke/heart attack/Japanese armor accident at any time.
Odds of Returning: 10:1

Paul Kinsey
 Played By: Michael Gladis
Last We Saw Him: Wishing Don had taken him instead of Peggy.
Why Stay: There's not much else for him on the horizon.
Why Leave: We have a feeling he doesn't want to, but if we're looking to streamline the cast, his peripheral character is an easy cut.
Odds of Returning: 75: 1

Sal Romano
 Played By: Brian Batt
Last We Saw Him: Calling his wife from a pay phone before cruising the after he was fired from Sterling Cooper.
Why Stay: Well, he is effectively gone, but the way his storyline ended, he always seemed like he'd be back for more. Plus his "gay in the closet" storyline has tons of ways it could play out and lots of modern day implications.
Why Leave: He is already gone. Don could rehire him, but their main client is American Tobacco, the company that had him fired in the first place, so that seems about as likely as a Judy Garland Resurrection Tour.
Odds of Returning: 100 : 1 (but we really want him back!)