Gonna spit out a hot take and say that if they're pushing for a Cars ride in the Magic Kingdom (as ill-fitting as it seems), the most ideal thing to do would be to essentially move the Speedway out of Tomorrowland and make it a dark ride with still drivable, electric four-seater cars.
It would be "lesser" than Radiator Springs Racers, but let's not forget that an IP getting an E-ticket in one resort and a C/D-ticket in another/others has happened before, Winnie the Pooh (Hunny Hunt > Many Adventures) and Frozen (Frozen Journey > Frozen Ever After) being two such instances. And cloning RSR would rob California Adventure of a major draw, something that it has benefitted from for more than a decade even after being taken back a square (and something I'd argue every park, even the MK, needs at least one of)