While Duel is a brilliant ride in terms of throughput the extended outdoor queue is still used occasionally on busier days. With rides like Nemesis for example not opening the upper extension which enters Air's ride area is a suitable sacrifice, as if the queue should extend out of the entrance it isn't really impacting anything else. However, Duel is situated in a small area, and should they need to extend the queue out of the entrance it would create a bit of a bottleneck, potentially obstructing entrance from Katanga Canyon, and also access to Waffles and Ices.
Plus, the queueline does contain some smaller elements of theming. I personally would prefer us not to loose any more of the theming we have on park
The issue also is which theme would an attraction there fall under? The path is designed to be leading you away into a creepy woodland, so bringing African themed attractions closer to it would spoil that effect. Likewise, having a spooky themed attraction in the area would detract from Katanga's theme.
Also, it's ok saying that there is space for an attraction there, but after you've built that how much room is there for a queueline? While Sub-Terra's buildings have a reasonably small footprint the queue is considerably larger, and sprawls much more. They would need to provide space for this when constructing any new ride.
I really think they're better off leaving it as it is personally. The pro of a new attraction if you ask me is significantly outweighed by the negative impact it would have on the surrounding area.
