Here is a list of launch game install sizes so not as bad as what i originally thought, however i am unsure whether digital/disk versions take up different space. I am now left wondering whether to cancel my disk based versions of BF4 and AC4 with the hope of being able to download them at a reasonable price and speed on launch day!
Source:
neogaf
Assassin’s Creed IV: Black Flag - 20GB
Battlefield 4 - 33GB
Call of Duty: Ghosts - 39GB
Crimson Dragon
Dead Rising 3 - 19GB
FIFA 14 - 8GB
Fighter Within - 9.2GB
Forza Motorsport 5 - 31GB
Just Dance 2014 - 22GB
Killer Instinct - 2.4GB (Source) // 3.4GB for full install, can play after downloading 2.4GB
Lego Marvel Super Heroes
Lococycle - 13GB
Madden NFL 25 - 12GB
NBA 2K14 - 43GB
NBA Live 14 - 9GB
Need for Speed: Rivals
Powerstar Golf - 3.9GB
Ryse: Son of Rome - 34GB
Skylanders: Swap Force - 15GB
Xbox Fitness - 246MB
Zoo Tycoon - 2.6GB
Zumba: World Party - 24GB