This. Independent braking systems with stand alone power sources. Never happening.
Besides (and forgive me, because most of my memories of EE are vague because I'm usually concentrating on not getting ill), I don't think the train itself has enough momentum to continue up any further than it does now, does it? I may be thinking of another attraction, somewhere, but it comes to mind that you actually get pulled up a bit and held in place while the switchback rotates and confirms alignment behind you.
Regardless, there are more failsafes on a coaster than (just about) any other amusement attraction.