If you are willing to spend $30 a month, what I would do is start doing that right now, but instead save that money, perhaps in a different bank account. That way by the time the game gets released, you could have enough for another Xbox One, or be pretty close to the cost of one.
Seriousily doubt that will or would ever happen. I can't think of one MMO that even does anything like that. In a case like that, you will definitely need two consoles. I don't blame you for wanting to enjoy the game with your wife like this, but alas you might have to fork over for the extra console, the Live cost and the sub cost.