On what axis is Chicago competitive with SFBA or NYC as a "tech hub"? On the obvious ones, like dollars of VC funding or number of tech employers, it doesn't even look close.
You had some serious engineering here: Western Electric, Teletype, Bell Labs/Lucent, Stewart-Warner, Illinois Tool Works, USRobotics, Admiral Radio, Shure, Abbott Labs, Baxter, Rockola, Seeburg, Williams Electronics, Bally, Zenith, and of course Motorola. Motorola alone seeded lots of other small companies in the area.