Not that the size of the community is likely to be a problem with God of War 4 (though there are most certainly going to be irritating people in abundance on the servers). The problem with God of War is that it’s such a perfectly crafted single player experience, with a strong definable lead character and an epic world. Kratos isn’t even in the multiplayer game, and rather than epic, multiplayer battle arenas are just that, arenas. It runs completely against the very point of the series! The resource drain implementing a multiplayer mode is going to inevitably going to impact on the single player game. Multiplayer doesn’t just happen, it always comes at the expense (to a lesser or greater degree) of the single player game, and I’m personally sick of single player games being used as glorified tutorials for the multiplayer that the developers desperately want people involved in.
The reason Dark/ Demon’s Souls and Journey have minimal multiplayer is as much a consequence of the developers working around an inherent problem with multiplayer – that is, the obnoxious people that play them, and the lack of integration with the single player experience – and have come up with a creative solution to them. That doesn’t work for every game, though, and for many games I would suggest rather than shoehorn in a multiplayer mode, how’s about doing something radical and putting the resources into fine tuning the single player game more?