Orion Assembly builds the Bolt EV, and GM needs somewhere to build all those EVs it's promising.
Many good things are built on the remains of long-forgotten bones. Heck, the entire automotive industry runs on rotten dinosaur carcasses. At GM, the poor little Chevrolet Sonic, the car that time forgot, is being put out to pasture, but it will be making way for the future of transportation. Cutting the slow-selling Sonic would allow GM to dedicate the Orion Assembly where it is built into increased Chevrolet Bolt capacity, and capacity for the multitude of variants planned on GM's EV architecture.
GM is planning at least 20 new all-electric vehicles by 2023, and the Bolt platform will be spawning a whole showroom's worth of models through 2021 at least, the latest rumors pointing to a high-performance electric crossover. More immediately, Chevy is asking the government's permission to start sending their Skynet-controlled Cruise AVs onto the unsuspecting roads in 2019, which have no driver controls but would be part of GM's Maven ride-sharing fleet. Holy crap, that's next year, already. In an interview with Automotive News, IHS Markit analyst Stephanie Brinley pointed to the inescapable logic of expanding the role of the Orion plant in EV and autonomous vehicle production.
This would be instead of dwelling on the failure of the American-built small car. "There will be new vehicles going into Orion," Brinley states, and that "the investment into that plant is well worth it" in order to work out the production kinks of building vehicles the likes of which we've never seen before. Tooling up any other plant would require significantly more investment than building on the first steps taken to produce the Bolt at Orion, and with the Cruise AV based so closely on the Bolt they will be the first to test the waters producing truly autonomous vehicles.