I would expect Gambrell and Kellman to be on the taxi squad if they aren't the healthy scratches since they need at least four there.
Gambrell has to clear waivers, so I think he's more likely a healthy scratch since I doubt they want to lose him for nothing (particularly if they want to be able to expose him at the expansion draft).
I think you're looking at this to start the season (* must clear waivers):
Starters (20) - Couture*, Kane*, Meier*, Hertl*, Labanc*, Donato*, Leonard, Noesen*, Gregor, Kellman*, Marleau*, Nieto*; Karlsson, Burns*, Vlasic, Simek*, Ferraro, Pasichnuk; Jones*, Dubnyk*
Scratches (3) - Sorensen*, Gambrell*, Middleton*
Taxi Squad (6) - Bergmann, Gabriel*, Händemark, Suomela*, Merkley, Melnichuk
Barracuda (13) - Gallant, Viel, Chmelevski, True, Blichfeld, Halbgewachs, Letunov, McGrew; Knyzhov, Carrick*, Meloche*, DeSimone*; Korenar
Europe (5) - Chekhovich, Dahlen, Ibragimov, Sund, Knyazev
CHL/Barracuda/Who Knows (5) - Wiesblatt, Robins, Hamaliuk, Kotkov, Emond
That exposes two players on one-year contracts to waivers, plus the three older Barracuda defensemen.
I think Merkley gets sent down to the Barracuda when their camp starts up (probably around 25 Jan), unless he totally wows the Sharks in the meantime, and is replaced by one of DeSimone or Meloche for the taxi squad.
It's also possible one of the forwards goes down to the Barracuda and are replaced on the taxi squad by a second defenseman to start the season.