That's becuase they go out of the E gates. There is quite a few. Many are SkyWest "at risk" flying, and I doubt those get upgauged to a E175/CRJ9. The other destinations could get upgauged with reduced frequency. Kinda like our SLC-EUG/BOI/FCA/BZN routes we've done.

Of those 75 Cseries, 35 are at least firmly C100 models that could be labeled true RJ replacement. They don't start arriving until spring next year, and are likely only delivered at 1-2 a month, likely mixed between NY & LA. I could see over time the long LAX-DFW/SAT/YVR/AUS/MCI kinda routes fading. But I'm sure it would take time. I could also see E175s staying west and 717s ratios placed more easterly. A lot can happen.