A 4 door Mustang should have a longer wheelbase.  That would help with the interior space. 

If it is going to be a Flat Rock product, the styling will have to conform to the Mustang's hard points.  So i wouldn't expect anything too dramatic.

Not sure if Bronco-based but would be nice to see something like a GX, that would allow Lincoln to have a similar lineup: Corsair - Nx Nautilus - RX Aviator - TX Navigator - LX new model - GX

What's wrong with doing a new Continental? They could charge significantly more for a Continental over a zephyr. 

I would do a Bronco based Lincoln with fixed roof and full lux interior. Like the Navigator but smaller, full BOF and 4x4 capability. Comparable size to Lexus GX, Land Rover Defender, and Mercedes G Wagen. It will print money. 

Comparing cost/ton of a freight train to a diesel highway truck is apples to oranges.

Have you been in a Mustang?

Ummm….. no.

in 2035 lol

Hear me out. A proper Lincoln Continental based on the mustang sedan platform. RWD, with elegant proportions.   The Lincoln l100 sketches looked so good when they actually gave it this long, dramatic hood. What ruined that concept was the decision to give it this short, stub nose look.    Taking this design, and toning it down for production, but trying to retain the striking proportions as much as possible, the road presence would be unreal. Paired with some sort of refined performance hybrid or something else with effortless power.