Assuming it is based on anything we can guess from the already written books, I had thought it might either refer to a future significance to Rhuidean, or else a sort of combined court of the thrones of Andor & Cairhien under one ruler. I wouldn't go so far as to make a theory out of this, because I am sort of hoping for a much changed world for the Fourth Age. Rand is supposed to BREAK the world, damnit! Not just give a few thousand people reasons to change their addresses. As it stands, the world of WoT has been "broken" less than Europe after World War One, and considering that that Trolloc Wars or War of the Hundred Years failed to rate that term in their books, the world of WoT as we know it continuing with some minor political adjustments and technological developments is kind of a let down. I would prefer the Court of the Sun refer to something entirely new on the completely different land mass that is left after Rand and the Dark One get finished thrashing the planet up one side and down the other.

Of course, there is also nothing that says the Fourth Age CotS has to be the same as the reference here. Cairhien is my best guess (how else do you refer to the court of a ruler who sits on the Sun Throne, in the Sun Palace, in a city called Golden Dawn? ) - perhaps the vacant throne is finally filled in this book?