From a practical perspective the answer is no (expense, bad PR, maintenance nightmare...) This will never happen. The purely academic answer is, it could be done. The Missouri cave laws protect the owner from damages and trespassing, and prohibit damaging the water system that the cave is a part of. If SDC could get permission from the owners to damage the cave, and the operation of the coaster did not damage the water system, it would not violate the Missouri cavelaws. The big issue are the laws regarding the Federal endangered species act. Since Marvel cave does contain these species, the impact of the coaster would need to be dealt with. There are many cases in which construction and use has occurred in environments that contained endangered species (none to my knowledge involving a coaster in a cave), but the process is incredibly expensive. So the answer to the question is no, the coaster will not be in Marvel cave.