How much do you imagine the once daily SFO-DTW UA flight on an A319, took away from the MSP-FNT flight? I'm pretty that flight alone was not the tipping point for the flight. Surely most who switched to that flight to get to FNT were already flying SFO-ORD-FNT, not SFO-MSP-FNT on DL. I'm going to bet it was mostly DL people who tired of flying the CRJ-200 to MSP when they could drive to DTW and get mainline non-stop routes out west, or mainline to MSP.
Who the heck is flying to Flint from San Francisco?