Im thinking shaft. It fits better with their narrative about going against cirrent design. But if it is a belt, in order to keep with what they are saying, its going to have to be a crazy design. Motor up front, down the middle, on the right side, or have a center diff or something.
However, given HPI/HB recent history, if its not a shaft, it will tank. People want different, but they want that difference to be a shaft.