Since we still don't have our last continent, here are the possibilities I can think of.
Leg 11 will most likely be in Australia & Oceania. I can think of Australia as the closest possibility, but countries like New Zealand, Papua New Guinea, Fiji, Vanuatu, Samoa are also possible I think.
Very off-route and unlikely, but if they do a penultimate African leg, that'd be great!
Antarctica?
I'm not sure how possible this would be, but if I'm not mistaken, it's summer at the South now right?
To conclude, I'm betting on Australia or NZ.