10x over 75 years is a ~3% risk-free annual return. It looks like ordinary government long-term bonds (like 30-year treasuries)
were yielding around 4% in 2008, making this look at first glance like a good deal for Chicago.
However, municipalities with a good credit rating can usually issue bonds that pay out about a third less yield than treasuries, thanks to favorable treatment of municipal bonds in the US tax code. I don't know how healthy Chicago's rating was in 2008 but even if somewhat mediocre, it's likely they could've gotten 3% or less on the bond market.
So at a minimum there was no advantage for the city in signing up for a sweetheart deal with strings attached, instead of covering the shortfall by issuing a bond.
However, municipalities with a good credit rating can usually issue bonds that pay out about a third less yield than treasuries, thanks to favorable treatment of municipal bonds in the US tax code. I don't know how healthy Chicago's rating was in 2008 but even if somewhat mediocre, it's likely they could've gotten 3% or less on the bond market.
So at a minimum there was no advantage for the city in signing up for a sweetheart deal with strings attached, instead of covering the shortfall by issuing a bond.