TARP funds included entities like AIG that weren't commercial banks, and Bank of America took over Countrywide's assets, and JP Morgan Chase took over Bear-Stearns' assets when the market was already failing, much of TARP funds did end up dealing with those assets. TARP funds also went to auto companies. At any rate, the market would have been hit hard even with Glass-Steagall.
AIG issued credit default swaps to insure securities issued by investment banks owned by commercial banks. With Glass-Steagall in place, investment banks would have lacked the leverage to do what they did to the level they did. In short, there's no need to speculate how hard the market still would have been hit with Glass-Steagall, because the scenario that played out simply wouldn't have played out.