Quadrasteer added substantial complexity to the beam axle (adding steering knuckles and outer CV joints, in addition to the obvious steering gear), in part explaining the cost. The lack of popularity would have been a combination of the cost, lack of recognition by buyers of the value of four-wheel steering (especially tech-adverse pickup truck buyers), and potential higher maintenance cost of the more complex system. Because the truck wasn't designed for rear steering, the Quadrasteer required wider rear track, which was good for stability but was undesirable to buyers otherwise.Four wheel steering is great, can't imagine why GM didn't think of that 20 years ago, and then implement it for 3 years, and then drop it.
In the current world these EV pickups will all have independent rear suspension (IRS), making the incremental cost of rear steering much lower. They're also designed from the beginning for features such as rear wheel steering. Buyers, even of pickups and especially of EVs, now crave any advanced tech they can brag about. With IRS anyway and tons (literally) of electric hardware in the vehicle now tolerated, I don't think there will be much concern among buyers about maintenance. The time has come for rear wheel steering.
All of the EV pickups that are going into production (Rivian R1T, Ford Lightning, GMC Hummer EV, Chevrolet Silverado) or likely to actually make it (Ram 1500, maybe someday Bollinger?) have independent rear suspension, and so will require four-wheel alignment, with only toe likely to ever be adjusted.
