Losing Undisputed and Van City is going to impact everyone's income. Stadium income is dependent on the popularity of both teams playing a game. With only five teams now with over 10 million popularity, what can we do to increase popularity? In an ideal division, every team would have 10 million popularity which means everyone gets a sellout.
Yes it really hurts to not only lose two top managers but also we all take a hit on the popularity. All I can suggest is that you concentrate on your own popularity. Buy a few popular players and try and get to 10 million. As soon as you do, you'll sell out regardless of the opposition.