I absolutely agree, which is why I think the raft ride (very low capacity) is much less likely than everyone is speculating.
The exit of a giant stage show would have to be very carefully executed, too. Dumping that many people out in a dead end behind the parade route would create a major pinch point.
I would really hope that any Frontierland additions would involve fixing the dead end and creating an alternative pathway to Liberty Square (either via bridges across the islands or around the land on the north side of the RoA).