It should be a consistently moving line and at 4-5k per hour, that tops peoplemover numbers in terms of capacity. So honestly I think it will be a very short wait. Longest thing will probably be going through security before getting on the gondola.
Angels will float down from the heavens and shoot rainbows out of their angelbooties if this thing gets anywhere close to 4000 an hour. Currently they top out at 5000 per hour USING 35-PERSON CABINS. IN A SINGLE-LINE SYSTEM. IN BOTH DIRECTIONS. So how exactly will 8-person cabins in a one-direction system cabins be able to manage this? Furthermore, when numbers like 5000-per-hour are thrown about, that also means people are getting on at multiple stations and few are riding it all the way to its terminus. For the Caribbean Beach Station to hit 5000 people per hour, that means 2500 people per each theme park line (people will not be heading to the resorts in the morning). 2500 people means 42 people have to be sent out on each line per minute. With 8-person gondolas, this means one car every 10 seconds. 10 seconds is the absolute minimum time these need to load (I've read "it takes 10 seconds to a minute to load each gondola"). Now we are talking about a clientele that has many strollers and wheelchairs, so not only will capacity shrink, but so will loading times.
The usual way these systems meet those load times is because they hit the stations and they basically become Omnimovers. They slow down enough to let people on, but they never stop. With all the strollers and wheelchairs and little kids here, that's not very realistic. I think the only way Doppelmayr will be able to hit those quick load times is to have a station like those seen on chairlifts, where the gondolas can be removed from the line, filled, and then put back on the line. The only way to do this and keep gondolas exiting the station every ten seconds is to allow many gondolas be removed from the line at once. So while one enters the station and people get off and other people get on, there are already several full gondolas in a queue to leave the station. That way, if there are any loading problems, it isn't affecting the car that's supposed to be heading out. Concept pictures of the Caribbean Beach Station do make it seem like this is how things will be done. Still, this still relies on the people using the system, and we've seen how some of them deal with getting on an Omnimover.
If they can't hit those 10-second load times, they are doomed. 20-second load times, with every gondola having 8 people in it, means only 24 people per minute leaving the station, and that's 1440 per line, 2880 PER HOUR. That's disastrous. Now do the math. The Value Resorts alone have more than 4000 rooms between them. At capacity, there's more than 12,000 people staying in those two resorts. Say one-quarter of those people are going to each park (not totally realistic with other places to go, but with Extra Magic Hours, one of these parks will have people lining up early, plus Star Wars will make DHS really popular when this opens, so let's just go with these numbers). That means 6000 people are going to Epcot and DHS just from here. Of course not everyone leaves at the same time, but if even half of those people get on the gondolas before opening, that's 3000 people leaving one resort all at about the same time. This isn't horrific because this line would be a straight up-and-back, meaning topping out at 4000 or so is highly attainable. But now those 3000 people are vying with the 1000-or-so people leaving Caribbean Beach (I don't know how many rooms they lost). Plus, those people who have just flown over from the Riviera, which is going to be fairly small (at first) so they're only adding one or two hundred people, so we'll ignore them. So now there are 4000 people wanting to go to two parks in one station. If they can only manage 20-second load times, some of those people will be in line for more than an hour. Also, say it's Early Magic Hour in DHS. That means the majority of the people in the CB Station will be going to one park and not the other. Even at 10-second load times, one line can only handle 2880 people an hour. Yes, this is a problem that only happens at park opening and park closing, but it's still one that can make guests psychotic.