Not sure if you've used one of these systems before.
The one in London over the Thames is pretty much what has been discussed for WDW. I used it to get back to the office after an event, and it took around 30-40 mins to get 100 of us back to the office. I think there will be pinch points where you need to change lines and merge etc, but I think with some pre-boarding videos in the queue they can speed it up.
The video below was taking in 2012 when it was new and you see a wheelchair be boarded, the loading area slows down to a crawl. Tourists are not very good at boarding it and getting on with sitting down!