1. Titanfall is 20GB on XOne, and that is mostly uncompressed audio so they don't have to decompress it on the fly. The PC version is 50GB because they use high quality high bitrate audio for all languages. This is not typical at all.

2. Games like The Witcher 3 show that they are more than capable of making huge highly detailed game worlds. Seriously the game world is apparently at least 20% bigger than Skyrim (with rumor that it actually covers 3X the landmass), with many more hand crafted quests vs Skyrim's mostly procedural quests.

3. Skyrim is only like 3.5GB yet RAGE a linear FPS is 25GB. Gameworld size doesn't really = disc size.

4. By doing things procedurally you can make the game world functionally infinite as shown by No Man's Sky that will have millions of fully explorable planets.

Lets not forget also that for games that are also available on 360 and PS3 they will probably limit the game world size to something those older consoles can handle. The limitation there is the 360's dvd drive I guess which has less storage.

Obviously new area data is streamed into the console when required from hard drive or disc so I guess the real limit is how much storage is available per console and how much of that world has to be simplified to fit into 400MB of memory compared to 4-5GB.

If Skyrim can fit on a 9GB disc(xbox dvd?), I'm sure with 50GB (double layer Blu-ray) we will see vast improvements in terms of scale, density and graphical fidelity. I think most space is taken up by video and audio anyways...

I personally think worlds don't need to be much bigger, just more responsive.

But they can maintain FMVs, CGIs on disk. 

http://mp1st.com/2014/03/08/titanfall-16-39-gb-xbox-one-35-gb-sound-files-pc-install/

30s on Google

Infamous is an open world game, gorgeous open world game, I wouldn't mind a game with a bigger scale and worse graphics since I guess it's doable.

you know what i think about stuff especially gta online.  they can easily make the city dynamic.  they can open up new buildings creating new missions for years.

Firstly, I disagree completely with the spirit of your post. Why are bigger game worlds necessarily better!? And GTAV is already huge - surely there's a point where it's big enough.

Secondly, The Crew seems to disprove your point as it's absolutely gargantuan. Additionally, we haven't seen an open world game that is traditionally huge on PS4/XBone yet (inFamous never had a big map). GTA, RDR, MGSV etc. are all still to come. So you are whining about something which hasn't taken place yet and for which there is absolutely no evidence.

Thirdly, your reasoning is terribly flawed: "open world games will have a hard time because they will not have enough disk space". The size of the game world is not limited by disc space. GTAV was on how many X360 discs? In addition to the fact that the disc size has nothing to do with it, the actual size of the game has little bearing on the world map as well. The amount of high res textures and other content on the disc drives up the disc size. For example, I could create a cell shaded 3 dimensional GTA type game with a map 1000x the size of GTA if I used generic buildings and low car and few variations of cars, people, plants etc. and I'd be able to fit that game on a PSOne disc (650mb).

So all in all, a poorly motivated thread backed up by terrible reasoning. It is very pointless indeed.

1-take a small map
2-copy it
3-change randomly the position of elements
4-paste it in other place
5-repeat 2 to 4 until complete a giantic map

you can have the map as huge as you want with a minimum HD space.
Variety of elements that can be a limit factor, but, 50 gb would be enough for mosts cases.

also, i thought the limit of this gen was 100 gb. you know, double layered blu-rays...

Game worlds will only be as big as developers want them to be. Gen 6 we had games like Morrowind, True Crime Streets of LA, GTA San Andreas, Driv3r, Wild ARMs 3, Test Drive Unlimited, etc. Gen 7 we've had The Saboteur, Just Cause 2, GTA5, Oblivion, Skyrim, Test Drive Unlimited 1 and 2, Infamous, etc.

With gen 8, no idea how big the worlds are going to be yet, but we've got games like Destiny, The Club, and The Division which are trying to push the open world experience. None of these games may be as big as Just Cause 2 or Test Drive Unlimited 2 which are some massive worlds, but I don't expect them to be small.

That is not true at all.  "Smaller is never better?"  There are games that benefit from having smaller maps.  Being too small is bad, but being too big is also an issue.  If you do not understand this, you have not played enough variety of games.