On June 15, 2016, sunset in Orlando is at 8:30pm (but it is not dark then - go outside tonight at "sunset" in your area and tell me if it is dark enough for a projection and laser light show - clue it's not). "Civil twilight" (when it is finally dark enough to see some of the stars) is usually 25-30 minutes after sunset. So say June 15, 2016 "civil twilight" is at 9:00. That would be the earliest possible show that night. So if the park closes at 11:00pm, Disney may only be able do 2 shows: 9:00 and 10:00. Since viewing capacity seems to be only 5,000 (per reports), then maybe they can get people in and out faster (and maybe the show is only 15-20 minutes?). If that is the case, maybe you could see a 9:00, 9:45, and 10:30 show. Historically, the first posted park closing times tend to be extended out closer to that date as Disney gauges crowd levels. So, you may see AK open until midnight in June and 1 hour spacing between 3 shows (or 4 shows with 45 minute spacing).
Sunset in Orlando is at 5:30pm by the time I arrive in mid-November, so that time of year will likely see a 6:00, 7:00, and 8:00 show - with a 9pm closing time (I am guessing with lower crowd weeks, maybe they only do 2 shows? But with a 5,000 person capacity, I am hoping they still have 3). My guy says that AK will have to be open 3 hours after "civil twilight" to fit in the shows and accommodate the crowds that shift from AM arrival heavy to PM arrival heavy.
If you like AK now, mornings at AK are probably going to be great as the 1/2 day AK folks won't even consider showing up until 4-5 hours before sunset, at the earliest.
What I do know is that I am definitely going to AK with an afternoon arrival and am saving all 3 fast passes for Sunset Kilamanjaro safaris, Rivers of Light, and Expedition Everest at night. I fear that we may see tiered fast passes go into effect for AK when the nighttime stuff opens. Maybe not since there are so few attractions that really need a fast pass. That Rivers of Light fast pass is going to be TOUGH to get. Plan accordingly folks.