Ok, massive spoiler update from "around" 'cause I tend to know a lot of stuff:
Yes, Katee Sackhoff's last appearance is in episode 16 "Maelstrom" (keep in mind that the season ends with "episode 19" as "episode 16" is really "episode 17" because they cound "Precipice" as "episode 1.5"
Anyway, it's not clear if Sackhoff is leaving the show entirely....or if they're toying with us.
That is, have her presumed dead then bring her back later.
Based on the writer's podcasts, the constant mentions that the Cylons feel Starbuck is "special" and "has a destiny" are so ingrained to the series that I don't think they'd casually remove her before this.
Meanwhile, in the upcoming Kat-centric episode "The Passage", we find out that Kat isn't really who she says she is: think about it, they're a refuge fleet. They don't have government records or official civilan records or whatever. Basically its something along the lines that Kat was actually a drug runner before the attack, and I think that "Louanne Katraine" is actually an assumed name. I mean they don't really have records of anyone's past so this seems plausible (Hot Dog, however, was a colonial academy washout and I think they would have records of that).