For Star Wars, I almost wonder if adding a few capacity attractions would have been a bit of a mute point. IMO the line to get into the land would have been the same at opening, meaning it still would have been (execs estimating 6-8 hours), and then add in the lines for the rides.
Except that adding a few more capacity attractions would have added to the capacity of THE LAND. Lets say for instance that Falcon and Alcatraz both have an capacity of 1,800 pph (seems to be about what I heard?). A 3.5 hour line then is holding (1,800x3.5) 6,300 each. Lets say FP has 50% capacity, knock that number down to 3,500 people in line (fp still has a line just not a large one). So we have 7,000 people in line.
Falcon is said to have 6 person cockpits, 8(?) cockpits per turn table, 4 turn tables, meaning 192 people on the ride. I have not seen any specifics for Alcatraz other than 8 people per vehicle and a ride time of about 8(?) mins. Assuming they dispatch 4 vehicles every 60 seconds, that would mean 256 people on the ride.
Total people in line or on ride for 2 attractions =~7,500 (lots of rough estimates in here)
Now, if they would have added the rumored "Bantha Peoplemover" concept.
Peoplemover moves about 3,600 pph. Assuming this lower ticket level only have a 2 hour wait, that gives us a line of 7,200 people. If there is fast pass, about 3,800. On top of that, people mover holds ~600 people on ride for a total of 4,400 people on ride or in line for Banthamover.
I'm not sure exactly how this would affect wait times getting into the land as now a ton of extra people have fp for the 3rd attraction and will get to cut the line, but I can say an extra ~4,400 will enter the land WITHOUT clogging up the stores, restaurants, and pathways.
TLDR: With 2 attractions and a 3 hour wait, ~7,500 people are in line or on ride. Adding a Banthamover changes that number to 11,900 people. It's a shame the 3rd attraction didn't happen