A later article (or video, forget which) specifically said there will be only one new luxury added to the game and it will be specifically tied to a new civilization.
I think there's a strong possibility that the new resource may be a produced resource, something that only a particular civ can make. Another thing that may be possible--which I haven't seen talked about, really--is that the new resource may be based on a tile improvement that "converts" an existing resource into this new resource.
For example, you could have something like the Ashanti, or a Native American civ, that has a 'loom house' or 'weaving house' improvement, something that turns a natural luxury resource (cotton, silk, etc.) into some other kind of luxury resource, like blankets, rugs, quilts, kente cloth, etc.
Such a resource may even be tied to the civ's UA, granting them, say, +2 culture (or something) for every source of the new luxury resource that lies within its borders. While still tradable, it would be a significant resource for the civ in question, as it would bolster their defensive culture output. Perfect for say, an early Native American or African civilization fighting against European colonialism.
This kind of resource 'conversion' would be woven (pun intended

Buffalo, seals, tea, coffee, tin, etc. just seem a little too banal and pedestrian the more I think about it; there's gotta be more to it than that.