We're not talking about one 747 a week to DTW. We're talking about replacing 6 50-seat RJ's a day (300 seats) and/or 4 76-seat RJ's a day (304 seats) with 3 717's a day (300 seats) on routes that used to be serviced by mainline 737's and DC-9's. As UAL AA and DL reduce frequency but keep seat counts stabile, pax will move back to mainline.

And I agree, business travelers do care about frequency. But they care more about reliability, and the last thing they want is to be sitting on the ramp in LGA or JFK waiting for a crew until their flight cancels.

Pilot availability is becoming more important than fuel costs. $130/BBL oil made 50 and even 76 seaters unprofitable. In addition, now that the big 3 are profitable, they look to reliability to ensure that business travelers can make their flight and get to their destination as planned. As DCI carriers lose pilots, they cancel flights, get penalized by mainline, lose future CPA's and shrink. Displacements and downgrades motivate more pilots to bail, which lowers their reliability even further. That's why DL is putting mainline 717's back on the shuttle. DL is rumored to be looking for even more 717's and RA was quoted in AW&S that he was interested in the C-series, which means that the E-190/175E2's may be in play. If that happens, it will spell the end of the DCI model as it currently stands. Like you said, mainline has too much invested in the hub-spoke system to let DCI problems affect it's reliability.

The only 50 seaters that will be flying 20 years from now will be in China.

Again, just my opinion. The goal is to bring all flying and RJ pilots who successfully interview to mainline, isn't it?