Chapter 9 is only for cities, counties and similar sub-divisions. There is no mechanism in the bankruptcy law for a state.
I’m confident, however, that the ultimate game plan is for the deeply indebted states such as IL, CA, NY, to push their liabilities off on the rest of the country via a Federal Government bailout. Grossly unfair to those states that run prudent finances, but he who has the most votes wins.
The solution for Illinois is to use Chapter 9 for Cook County (where Chicago is located) if things in Chicago get out of control. That's probably where most of the economic problems of that state come from.