Forgive me, my-dear-fish, but I feel compelled to interject; it ultimately boils down to perspective and truthfulness, and while I know we like to avoid 'X might be lying' because it ultimately throws everything up in the air, I think this may be appropriate here. Vivec, a God-King, claims to not sense the dwemer anywhere in space or time; I can't remember with certainty if his statement extends beyond Mundus, but I think this was the case. Set against this, we have Yagrum Bagarn, who is, as far as we know, the Last Living Dwarf, very plainly within the fabric of Mundus.
It's important to note that the player has already met and intereacted with Yagrum extensively at the point Vivec says this. There's no point in Vivec mentioning Yagrum, he knows you know Yagrum's story, and therefore is addressing the actual question of the race's whereabouts.
Addendum: this is in no way a denial of the Golden Skin explanation, simply the assertion that more may be going on than is readily apparent.
There is more going on, much more, and there are many unanswered questions. The article on the Dwemer's disappearance makes it abundantly clear that there is more going on, and should make it clear that all we really know is a general outline of their end goal, and the fact they were bound to the Numiduim at some point (and perhaps continued to be). Everything else is still up in the air. Yagrum, their success rate, their plans as they relate beyond the Dwemer (since the Numidium wasn't just meant for that one time show), the extent of their pre-disappearance immortality, all kinds of fun questions.