Good point...yet at the same time I think the airlines are very wary of fuel price spikes now, even with it down around 70/bbl, and any opportunity they have to replace 50 seat feed with tprop feed and 76-seat feed (=first class money for nearly the same operating cost) might be taken as a strategic measure, even if 50 seaters get into the black again.

On the other hand, DAL seems to be pretty "image conscious" with regards to their feed, and past decisions (wanting to phase out ATRs in ATL, and on any routes that didn't specifically require them) make me think they would rather keep an RJ on a route for slightly more cost as long as they're not losing money on it...due to the marketing aspect of offering "jet service (puke puke)" to some city they feed out of.