Over the summer, Abbey creator Julian Fellowes admitted that even he didn’t know if the Emmy- and Golden Globe-winning actress would be back. “I can’t tell you, ‘Oh, yes, she’s definitely contracted [for Season 4] — because she isn’t,” he said. “It’s entirely up to her when she stays and when she goes.
“With Maggie, you never know,” he added. “Other [actors] sign on for the next series and they sign for this and they sign for that, but she doesn’t. She stays her own person. But as far as I’m concerned, I hope she stays with the show until Downton falls down.”
[WARNING: MAJOR SPOILER ABOUT SEASON 3 APPROACHING... ]
Smith’s decision to stick around ensures that all of the show’s major castmembers are on board for Season 4, with the exception of Jessica Brown Findlay and Dan Stevens, whose respective characters, Sybil and Matthew, are killed off in Season 3.