Salute!
Another solution that keeps the basic construction jigs and such in place for building more dinosaurs was proposed earlier here, but will still require certification, just not as much. Expensive, yes. But not as expensive as all the $$$ that will be paid out to the families and possibly airlines with useless airframes on the ramp.
Ditch all the STS, feel system, MCAS and such crapola. Go FBW and retain a few of those ropes, levers, pulleys, tubes and such that some here still prefer for a modern airliner. You wouldn't have to worry about control force versus AoA or "Q" or mach gradients, just ask the Airbus folks how they got by the FAR 25 requirements. And you knoiw what? I don't think the FBW version of the MAX would pass. The design is not as inherently as "nice" and gentle and forgiving as it should be.
The 'bus showed its inherent stability and pretty good aerodynamic characteristics on at least two crashes - the "showboat" public relations pass and AF447. Without all the "protections" and such, most pilots could fly the thing in the "direct mode" and get it back on the ground in one piece. After all, FBW primarily means replacing all those mechanical connections with a hydraulic source and an actuator commanded by an electrical signal. You do not even need a computer to have what the 'bus calls "direct law".
So I have a feeling this "fix" is gonna take a lot more time and $$$ before many carriers and countries are gonna buy in. I wish Boeing well, but I also wish Boeing would get back to the basics that made them one of the premier aircraft production empires in aviation history.
And just so you know, I never flew a single model of anything Boeing ever built. I flew McDonnell, Cessna, Lockheed, Convair/General Dynamics and Vought.military planes , and on the civilian side Luscombe, Piper, Aeronica and Taylorcraft.
Gums sends...