I agree with many others here, I think I’d prefer a 175 over any other narrow-body in DL fleet (*except a D1 seat on 752). I love that they board fast, have big and well placed windows, seem quieter than CR7/9, roomy seats, option for 1 seat side in F and no middles in C+ and Y.
I’d be all for the 175 becoming the domestic equivalent of the 787, allowing for more point-to-point, long distance flights instead of hub and spoke on 737s, 321s etc. How is the 175 operationally for airlines (I would guess that it doesn’t offer a big efficiency bump like the 787/350s)?