My bet is on Phoenicia and Tyrian Purple.
It's not going to be something clever and subtle, when we're given hints we're always thinking too much about it. It's going to be something stupidly obvious or cheesy, not something subtle, interesting or unique. This isn't for Scholar, it's for the average person, and sadly most people don't even know what Tyrian Purple is... as sad as it is to say most wouldn't even know about Phoenicia.
Batik for Indonesia. It'd be obvious if that was revealed as well.
I'm gonna throw my hat in with the Inuits.
I don't think he means the resource will necessarily only be available to this new Civ, but that only will be in a position to benefit the most from it. Thus if he said Seals was the new resource which spawns on snow/ice/tundra we would all jump immediately to a civ which would have this area as starting bias and unique aspect to their play.
Although pastures are the only non-unique improvement tile with no luxury resources associated...
Not revealing it was due to it making them too obvious, not only them using it. The Inuits are an option, but Seals are hardly entirely exclusive, and honestly I don't exactly see how an Inuit Civ would work.