I'd rather be poor in Chicago than wealthy in Phoenix
The budget crisis is serious, but not like the city will (or could) be liquidated and sold at auction. Pensions are typically funded at a 75 to 80% level. Illinois currently funds at a 50 to 55% level. That's not THAT underfunded. There's still time to pour money into the fund. And if it doesn't happen, then the payees will take a haircut (though there's an Illinois constitutional argument against that) OR other city services (read schools, construction, and city services) will take a haircut.
Trash will be collected half as often. Classrooms will go from 15 students to 25. Highway lights will be shut off to save money. Etc.
By no means is this crisis inevitable, nor will the sky fall on Chicago. Illinois cannot go bankrupt and you go and purchase the land. It doesn't work like that.