I wonder - did Someshta know the song that the Tinkers were looking for? Did any of them ever track him down, but didn't make it back out of the Blight afterwards? There's potential for a tragic short story there.
My guess is that he was somehow tied to the Power via the Eye, and when Rand used it up he lost his extra abilities. We don't really know much about the rest of his race, but they didn't manage to hang around for thousands of years.