So this will take a few big leaps of faith.

Assuming we can create our own settlements, assuming we could get together and elect leaders and organise militia to defend ourselves, assuming lot of people did this in other settlements, and assuming that these settlements would band together to form a Republic of City States.

Would it still be Fallout?

I mean, at what point does it stop being about surviving the wasteland and become a different game, and is that what people eventually want?

I believe this still would be Fallout. This would show that the game and the world would be evolving and that the people of the wasteland would be trying to rebuild. I believe that this is "One small step for man, one giant leap of mankind..".

Maybe a "game master", tuning up the weather a bit. Or if its gonna have some resources then resources run out, and a florishing city suddenlty turns into an abbonded one, ultimatly becoming a raiders nest. The Sarmatians

That is why there are still nukes plus other hazards to ruin your GECK paradise...

Here are the possibilities -

1) Unused Nukes
2) Mutants - Humanoid and animals
3) Raiders
4) Large Militias\Factions\New Governments (aka Enclave) that feel that you are rebelling against the USA or European Union or whatever and that you must be assimilated into their collective at all costs. Ok maybe they are not the Borg (although you never know), but they are psychotic and feel you should be a part of them or you are rebels. Some of these factions maybe heavily armed with tanks (modern and futuristic), have power armor, and other things and have a huge numbers of personnel.

So don't rest easy in Fallout. Remember you are the FOOL that left the Vault in seek of either survival because the vault failed for whatever reason or for individualism that a sterile vault environment does not provide.

FOOL should have a dual name -

1) Means Fallout Online
2) And that your toons left the vault to go live amongst the ruins and contaminates of the world ... lol

Survival after the apocalypse means rebuilding society.

I don't want to live in a crappy shack forever....actually I'm a huge post-apocalyptic fanboy, I would probably love it.

Sure. Ever heard of the NCR? The Vault - Fallout Wiki * Fallout Online * Fallout IRC Channel * Fallout: New Vegas

Dude, Enclave is dead. But post-Enclave factions could exist, some might join the BoS, some might still try to carry on their original mission, others might just weave into society.

this game is going to happen before the third game

By FO2 era there were some significant social hubs either brewing or established, even trade between them in the form of caravans. Actually in FO1 this was the case as well. While the maps themselves may have only represented a few small blocks of reclaimed buildings, I always assumed there was more to them that we just did not need to see.

So, (taking the OPs assumptions of course that player-based communities will be possible--which I am not yet convinced of), it really makes plenty of sense in the FO universe. And, as stated by several replies, the chances any community springing up in the wasteland being able to survive for long are likely slim. This would probably be true not only of a RW anolog, but also in terms of just getting enough players to stick with it long enough to make a semi-permanent community actively grow.

Argueably then, I doubt that players roaming the wastes looking for adventure and resources will be or even could be replaced by city-building simmers turning the wastes into a "Civilized" network of city-states. Not trying to be argumentative here, just voicing my opinion.

In a nutshell, player behavior will shape what it's like to play the game socially, but the design of the game will determine how that can manifest, which in turn will probably help shape player behavior to some degree. That said, iirc, the Devs themselves have stated that FOOL will take place in a time of rebuilding, so if players can figure out how to play into that concept in some way, all the better.

I doubt we need fear "Losing" the feel of FO however, I have confidance the Devs want this title to succeeed and are counting on FO fans to support it based on their love of FO not any (possible) love for MMOs exclusively. If this faith in the Devs is warranted, then they will manage a FO world we can all be proud of and look forward to playing in.

Oooohhh How fanboi was that...? Heh.

My two caps...

Settlements may rise and fall quickly in the wasteland. Constructing anything permanent and long-lasting should be a very difficult proposition. Thus if someone is able to pull it off for a good while... well, that would be rather awesome now, neh? And naturally make them a bigger target for all their enemies (player or NPC) wandering about.

Considering the developers will have control where player "settlements" can be set either directly through code (e.g. persistent containers/only certain places where "contruction" will work etc.) or indirectly through a survival mechanic so settlements only arise close to water or someplace worth taking water too. Nicer cities with the same old harsh wasteland in between is pretty doable actually. Also allows a larger world with less design needed. So long as players can't notice a pattern in the meshes *cough*or rocks, F03*cough*, it's reasonably easy to create kilometres of barren dirt. So long as they can be travelled whilst logged out (if so desired). Why do games studios have to fight and die? War, war never changes : (

I see the fallout era very much like a modern twist on the American wild west.
Now, I'm not very good with American history, but to me the 'Wild West' wasn't a short perod of time.
It may have started with the exploreres/ prospectors moving west, but went through the gold rush, settling towns, army/indian wars, all the way to the introduction of railroads and steamboats.
I've seen plenty of Westerns where bandits rob a train just as often as a stagecoach for example. Both iconic images of the time IMO.
Relating that to Fallout, I don't see the creation of towns as a finishing move to the era, or even the establishment of organizations like the NCR. As long as there are raiders, slavers, muties, ferals, or general untamed wilderness I think the feeling of the setting can be preserved.
If we get to a point of safe, regular caravan routes, easy exploration, fully detailed maps, mass transit, etc. - those would be the final steps into the 'post-Fallout' era.

The Wild-west in America only lasted twenty years. It was considered to be short. Well I guess we're just a couple of problem solvers