"I'm sure Disney knows what they are doing" is not enough reason to ignore the obvious: a gondola without AC is hot in the summer. Look at the gondola system in Spokane, Washington: it's website clearly states that when the temperature gets up, they shut the system down until "the cabins cool off". The only thing is, Spokane get hot maybe 20 days out of the year, whereas Orlando gets hot more like 200 days, and all day long during the summer.
And speaking of Disney knowing what they are doing, tell me why All Star Movies has stopped their renovations? They did half of their preferred rooms and some of their standard rooms. The least they should have done is finish all the preferred rooms rather than doing some standard rooms. That way, at least you can guarantee yourself a refurbished room by booking preferred. The cost of renovating is known from the beginning. It's like the Bible says, a guy builds a house without counting the cost, and he runs out of money half way and becomes a laughing stock. It's not like Disney is a guy who lost his job unexpectedly and can't afford to continue to build his house.
Another thing is, notice that in all the Disney updates of the Skyliner, including the video with Mickey standing in front of a gondola cabin, they never mention the fact that the gondola will not have AC but has natural venting. Why are they so careful to not talk about it? The windows don't open, and clearly visible is one row of tiny slots along the bottom that is the only ventilation available. And you don't have to be an engineer to imagine how much cooling that is going to provide, even if the gondola is going at 20 miles an hour.
What Disney maybe is banking on is that people will get on the gondola even if it's hot, at least most people will. It's new, it's fast, it's exciting and you can see scenery, a little bit of sweating doesn't hurt anybody. My husband works in construction and says that sometimes in the summer, he has to work for hours in somebody's attic where it's over 100 degrees. He hasn't died or anything.
I myself am planning on using the Minnievan when the Skyliner takes out the buses. Somebody's got to spend all that money my husband makes. But I will use the Skyliner at night when the sun's gone. I'm very much looking forward to it. I hope the Skyliner opens in September 2019 when I go, but I fear that they might not open till after October.
I have a personal theory: being that Disney has announced that the Skyliner will open in fall, despite the fact that all evidence points to the gondola being ready much earlier, I think Disney is planning on running the gondola only during the cold season, like from October to April. That will cover the entire busy season of Halloween, Thanksgiving, Christmas and Spring Break. I want to write down my theory here so that if I'm right, I can point to it later and show everybody how right I am! (If I'm wrong, I will keep my mouth shut and nobody will remember.)
I very much hope that I'm wrong on my theory because I only go in September, so if they never open then, I will never get to be on the gondola, and I really want to try it. I live near Spokane and we are cold all year except for a brief time in the summer. If I'm going to Disney World, I want to enjoy the heat and air conditioning!