Heyas FtB,
Replacement 100 seaters do NOT have to be expensive.
Take a DC-9...maybe with a new wing with better high altitude performance / more fuel. The airfame structure itself is PROVEN by 50 years experience.
Normal cabin and cargo capacity.
Simplify the systems a bit. The 717 would be a good model for this.
Where you can, have STONE SIMPLE systems with good dispatch redundancy. Anyone who's ever turned a wrench on a DC-9 or 737 should be able to fix it.
What you don't need is a MD-11 cockpit. Two IRUs, two comms, a simple FMS with BASIC RNAV capability (no need for RNP in the states). Think of something along the lines of a F-100.
No fly by wire. No hydraulic powered flight controls. No complicated engines. Roll it down hill, let the clutch out, and off you go. You should be able to practically pull start the engines.
Nu