First point conceded... was not clear from original post.

As to second point, current schedules from ATL to IAH show 4 mainline and 4 RJ flights per day.

If you want to claim "mostly mainline" is on a seat basis, I'll concede. But, as for the number of flights daily, and the opportunity to avoid a tiny tin tube at a particular time of the day, 50% mainline flights is hardly "mostly."

50% mainline is a big change from the historical 100% mainline.

As to the broader issue of just how interested DL management is in Houston in general... The four mainline flights from ATL to IAH are basically the only DL mainline flights into IAH from any DL hub (there currently is one flight from MSP but it appears to be going away in a week or so).

Here is the run-down in terms of HUB, number of RJ flights, and number of mainline flights daily:

ATL ...4...4
DTW...4...0
MEM...3...0
JFK...1...0
CVG...2...0
SLC...4...0
LAX... no direct flights

When I look at these numbers, I read not very much interest in Houston from DL management.