For reasons previously mentioned by me and others, I definitely think TAR 28 will be visiting Oceania this season. I think Australia is a lock, but there is a reasonable chance for Fiji to be visited.
Asia: Indonesia and Vietnam are the two SEA destinations that haven't been visited recently. The Arabian countries are also in play.
Africa: The last 3 seasons have featured Africa, but it is a fan-favorite continent, so toss-up; if it is visited, I'd imagine South Africa would be the most likely option.
Europe: Many good places in Spain to visit. I'd imagine there will be a winter leg somewhere, so Switzerland, Austria, and Italy are likely.
Americas: No visit to S. America this season. A surprise visit to Central America or the Caribbean is doubtful, but possible.