As other said, it's easy to mod in new metals.
As for them being officially added, I was under the impression Toady tries to distance himself from borrowing to heavily from tolkein and the like, which is why we have adamantine (which has ancient origins) rather than mythril (which originated with tolkein) and why we have goblins (again, old as fuck) but no orcs (tolkein). Dwarves and elves are both from germanic mythology and tolkein borrowed them, so many of the traits DF dwarves share with tolkein dwarves is just a matter of the germanic origins (living undergound, craftsmanship, hairyness) and predated tolkein, basically the same can be said of elves, a lot of what DF elves have, tolkein elves had, and so did pre-tolkein elves. The thing I'm most curious about is where toady got the idea to make the pointy-ears cannibals, it may be to reflect that in myths elves tend to be of questionable morality.
As for including TES materials, I highly doubt toady will do that, he seems to enjoy sticking to old/ancient sources and only lightly drawing from modern ideas (eg. the type of goblin found in DF isn't the same as one would expect from the myths, they seem closer to tolkeins - and before the "add orcs too then" things comes up, goblins and orcs, the two are used interchangeably in some of tolkein's work, and in others orcs are a type of goblin, so to have both as a species would be somewhat redundant)
Anyway, the point: I don't think toady will be borrowing any metals from tolkein, or TES, or any other modern fantasy pieces.