There is going to be a ton of after release features added. They are only in feature lockdown until release. After that, we will get more stuff according to recent dev posts. I think they are probably waiting to see how well the game is received before making any concrete promises.
But since I don't work for them, we will get:
-Lord Xia's Pony
-Lots of new mod capabilities (The Workshop, FE XML Editor, Mod Bugs Fixed)
It all comes down to the metascore though. If the score is ridiculously low, the after release content might be cut and added to the expansion.