Yup, the idea is, you already can own a house in the 5 major holds. The new houses are being built in the 3 lesser holds. And Winterhold fell into an ocean, so thats not an option.
If you complete the College's quest, you get the best studio apartment EVER IN THE HISTORY OF THE WORLD, and you have a whole University at your disposal. The only downside is that there is no smithing station.
I'm just stating this because essentially by doing those quests (sorry thieves and warriors), you get the 6th house, and with these three you now have the ability to have estates in all 9 holds. If the College of Winterhold isn't good enough for you, then oh well. It's not like it's hold with any real big major features except for the shrine of Azura, which if you're a Dunmer, you're probably using some sort of magic.