<i>Brothers & Sisters</i> Brothers & Sisters

Brothers & Sisters' Walker family has overcome cancer and a miscarriage this season, and it has dealt with the loss of the family business. What else could go wrong?

Finale Preview: Get scoop on 31 must-watch season-enders

From the look of the promos for Sunday's Season 4 finale (10/9c on ABC) — a lot. The episode includes a massive car accident, and it appears that at least one Walker won't survive. So, who?Well, the show can't go on without Mama Nora (Sally Field

). Who would hold everyone together? "She is there to save her family, and I think in the finale, she is mostly invested in making sure the family stays together," executive producer David Marshall Grant tells TVGuide.com. With Nora through the episode is Sarah (Rachel Griffiths), as the two join Kitty (Calista Flockhart) on the campaign trail. Based on what Grant has planned for Sarah and Luc (Gilles Marini, who reportedly will be a series regular in Season 5), Sarah seems an unlikely candidate for a dirt nap.

Check out photos of the Brothers & Sisters cast

"I think there's a lot in their future," Grant says. "I think as Sarah fell in love with Luc, so did the family and so did America. He's such a great, charismatic guy. We're going to definitely leave them on a high note. He's been great for Sarah."On a similar note, Grant says, are Kevin (Matthew Rhys) and Scotty (Luke MacFarlane), who found out their surrogate is pregnant. Grant says while biology takes it course, Kevin and Scotty will help Uncle Saul (Ron Rifkin) explore opening a restaurant. But, Grant teases, "they go through a very intense story as well."Justin (Dave Annable) and Rebecca (Emily VanCamp), meanwhile, consider a trial separation to deal with their growing marital problems. "They are both starting to see very different futures for themselves," Grant says. "I don't think it's in any way a question of their love — the clearly love each other. They just have two different ideas of how they want to live their lives. I think that's often the case with young couples: You just have to figure out how you're going to do it together."

Rob Lowe to exit Brothers & Sisters, "in talks" for new ABC franchise

That leaves us with Robert, played by Rob Lowe, whose announced departure from the show make him the most obvious candidate to die. And considering Robert's recent dealings with Bill Stanton (Patrick St. Esprit), who Robert was trying to catch in a political corruption scheme, there are plenty of ways for Robert to leave the show — alive or dead."This situation with Stanton could turn dangerous for him," Grant says. "He also certainly has his health to worry about, which has been an ongoing issue for him. And we have the relationship between Kitty and Robert, which has been up and down and could certainly hit a crisis if the situation with Stanton became a problem for Kitty's campaign. There are many options, and we had a lot of fun with that in the finale."Even so, Grant says there will be a possibility for Lowe's character to return in some capacity in the future.

Brothers & Sisters: Will Kitty's run for office divide the Walkers?

So, who's going to die? Since Grant confirms that the show is considering a significant jump forward in time between seasons, it really could be anybody."As we approach next season, we're going to see people in very different circumstances," Grant says. "Regardless of whether we jump a year, I still think we're going to be in the position to shake things up. But if we do choose to do that, then all bets are off."The possible time jump won't keep the show from producing a juicy cliff-hanger, Grant says, adding: "A lot of things are going to finally become clear to the audience, and at the same time, we're going to be left with a lot of mysteries."