Regardless, do you think it's unrealistic to expect another DLC from Skyrim.
My personal thought is no, it's not. Why?
Skyrim is Bethesda's most successful game, and with the PS4 coming out late in the year/early next year they will probably not be releasing any games on this current generation of consoles. They are going to want to make more money off of the game before the next generation arrives. On top of that, they'll probably want to just have the same amount of DLC that Fallout 3 did.
Bethesda hasn't come out and said that Dragonborn is the last DLC, so this leads me to believe it's not... simple.
While the Xbox 360's achievement point limit is 1750, Fallout 3 only had 1550. Skyrim is currently at 1550 with less content than Fallout 3, and most triple A titles, like Skyrim, have 1750 gamerscore.
Lastly, on the Bethblog, it was clearly stated that they want to support Skyrim through 2013. The only thing that comes to mind is patches and DLC, and I wouldn't see them supporting the game with only patches for a year.