Recently Narset Transcendent exploded from being about a $5 card to a $12+ card. I had thought that this was another move based on Commander, or perhaps it was simply that Narset was a popular character and a planeswalker, though this turned out to not necessarily be the reason for the spike.
As it turns out, Narset is starting to show up as a 3 of in a Modern Esper Control deck. As Modern slows down, a Lingering Souls shell with some planeswalkers could definitely be a powerful option, especially with Fatal Push entering the format. I would be concerned about this deck's Tron matchup though. Presumably that's what the sideboard Geist of Saint Trafts are for, but even with them I would expect that matchup to be extremely unfavorable.
While I like a lot of what is going on with this deck, I have never been terribly impressed by Narset Transcendent in constructed Magic. This seems to be a flavor of the week thing in much the same way that Zur the Enchanter was previously, and the real strength of the deck is Lingering Souls and Snapcaster Mage. I also imagine that Gideon, Ally of Zendikar Emblem is going a lot of the heavy lifting.
I expect that it will be some time before we see a Narset reprint, and the card also presumably has a sizeable casual following. That said, I wouldn't expect more immediate growth, and I also wouldn't recommend this buy to Modern players. I would be happy to sell off Narsets at the current price point.