I don't see why aftermarket products can't come in and better what the digital systems have to offer.
Take power: the systems provide transformers with AC or DC output with just enough amperage to power the required number of cars. An aftermarket power supply could offer better power allowing the user to change motors and upgrade accordingly.
Take controllers: The standard systems look ok, if not a little boring. Just wait until the guys at Parma look at how they're made and we'll soon see aftermarket controllers in all shapes and colours offering gadgets that we haven't though about yet. What about lights, sound, speed control, variable acceleration and adjustable brakes - all are possible with digital.