I have read that the Islanders are guaranteed $50M per year from the Barclays Center plus the local TV contract of $25M per year from MSG Network.  If these two numbers are correct I am sure that with other revenues that they team makes enough money.
Maybe the issue is that Barclays Center is being asked to do renovations to make hockey easier to sell in the arena and that is what is causing them to balk at keeping the team in the building.
Here is the article that I read guessing at the money from Barclays: 
http://www.thehockeynews.com/news/ar...arclays-center
It will be interesting to see the outcome of this.