In the past, whatevever mysterious powers control the Warehouse (or if the Warehouse is a living entity, sort of like Moya the spaceship of 'Farscape'), it was decided that the Warehouse would eventually go to the next country of great development. So the choice of China would probably make sense.
But what if the Warehouse decided it was time to think of Earth Prime-Time as one global community? Wouldn't it be a better choice for the Warehouse to position itself in a place accessible for all Mankind?
Why not Antarctica?
Personally, I would love to see the Warehouse take up residence in the Arctic Circle. And it wouldn't have to be specifically spelled out, but perhaps it could occupy the carbon footprint of Superman's Fortress of Solitude. In Earth Prime-Time, he no longer has any need for it... being dead.
That's just my wish-craft, however.
But I think Warehouse 14 being situated in the Antarctic would be the more logical choice. Going to China just doesn't feel right......
We'll find out later tonight with the series finale!