Good question! I'd imagine a pulley kind of thing mounted to the track.Off subject for a sec but has anyone seen how they get these coasters back to station after an estop or other failure. I saw a bottomed out HRRR back a few months after it opened and never stopped to wonder how they would get it out of that first deep valley.
So its time for this to become a reality then:
If that's truly a hint of the new style of the attraction, that would seem to indicate that it will not be themed to the Marvel Cinematic Universe version of the Hulk.