Many already speculated that there might be additional housing for the expansion, but there's on glaring problem.
How will Ishgardians welcome in foreigners to live on their land, when they've been so adamant about exclusion, even if there isn't an on-going war?
Granted there are a few Ishgardians who are more accepting, or even fanatically obsessed over our hero... (I'm looking at you Haurchefant) but that only accounts for a small minority. Even if we happen to "save the world" again, I don't think it'll warrant the Ishgardians to welcome foreigners into their borders.