Well...if history tells us anything, it is that parks open "unfinished" (as some people would say) and then get "capacity improvements" as needed.
Epcot opened, and within 4 years had 3 additional pavilions in FW, and a new country, with another pavilion and country under construction.
MGM opened with rides like Star Tours planned, and they were added a few years later, along with a host of other attractions.
The difference that I can see is DAK has NEVER been pushing its capacity mark on a long-term basis......not like MGM, which was only built to hold about 2/3rds the attendance it was getting.
(Yes, even the MK was built under this same idea....)
Now, DAK has seen capacity improvements (Asia aside, as that was really an extended phase 1) with Dino-Rama and now Everest. While I don't think DAK is near its potential, with EE opening, and a new show opening this fall where Tarzan ROCKS! was, that is some significant investment.
One thing I noticed now that EE is open......whereas I usually get to the park around 3:30pm, people would be leaving in masses......and if they were not gone at 3:30, they ran out of the park after the parade. With EE open, leaving at 5:15 was as bad as leaving the MK at closing when Wishes plays at closing......that many people were still in the park. EE...which will most likely have a 60-90 minute wait on most days, will add an additional hour or 2 to most guests stays.....the new show will add even more time......so DAK, being open until 5pm, might actually see most guests stay until 5pm.....
The next trick is to extend the closing time, and still have people stay until closing.