Even though the next gen consoles have an increased amount of disk space, the consoles will not have huge worlds this generation. Because games run at a higher resolution, open world games will have a hard time because they will not have enough disk space.
Titanfall is an FPS, the game takes up 40 Gigs on Xbox One because the shooter has a higher resolution than the 360 version (6 Gigs ish). A game like grand theft auto 5 running at the same resolution as titanfall (X1) version would probably take up 80 GIGs this generation!
Either games need to be tweaked to run more effecient or this gen is screwed because of disk space!
The Upside to this is if you are playing an open world game I believe loading times will pretty much disappear and be hidden in the background like Dead rising 3!
I really hope rockstar can make game worlds twice as big as GTA5/Red Dead Redemption and have them run smoother and at a higher resolution but we will see!