When The Vampire Diaries died this past March, so did many fans' hopes that Caroline Forbes and Klaus Mikaelson would ever end up together. Not that the show crushed their dreams entirely, in fact, the series finale of The Vampire Diaries strongly implied that Klaus and Caroline would be seeing each other again in the future.
The original vampire sent Caroline a hefty donation to fund the Salvatore Boarding School for the Young & Gifted (i.e. a place for all those supernatural children running around Mystic Falls), and he also insinuated that he planned to see her again someday in the future. Given that Caroline's husband — and one of the show's protagonists — Stefan Salvatore, died in the finale, it would seem that Forbes is now on the market once again.
#TheVampireDiaries sister series, The Originals, was recently renewed for a fifth season, and has since generated quite a bit of buzz surrounding the couple (affectionally named #Klaroline by fans). At the end of the latest season of The Originals, Klaus sent his daughter to Caroline and Alaric's school in Mystic Falls, leaving the door wide open for a reunion.
Speaking of "open doors," back in March, Julie Plec, The Vampire Diaries showrunner, gave a post-mortem interview to Entertainment Weekly on the show's series finale, and had this to say about Klaroline:
I can’t make any promises for many reasons: One, because we don’t have a fifth season of 'The Originals.' Two, because while I love the world of the boarding school and all that it represents, that would be an entirely new show that I haven’t even begun to think about, but the doors were not left open unintentionally. They’re open with a hope, not a promise.
Since the time of that interview, #TheOriginals did indeed get renewed for a fifth season, and now it seems like fans of the couple are about to get their wish. TVLine reports Candice King is confirmed to reprise her role as Caroline Forbes in the season premiere of Season 5. Additionally, Plec will be taking over the reigns as showrunner from Michael Narducci on the spin-off, so it looks like we'll get to see exactly what Julie meant by those "open doors" remarks.
It remains to be seen whether or not King is planning to stick around beyond a one episode guest appearance, but I would say that the odds are in favor of her being in it for the long-haul.