See to me there just isn't any reason for there to be that much prep going on right now.
I mean in terms of general peoples concepts of fearing a god war they don't really have a whole lot to go on - most of the history of the first god war isn't exactly public knowledge and it happens thousands of years ago its not exactly a fresh memory of trauma for most people. I mean the 4th Age which came between the war ending and human dominance through runecrafting was 2,000 years and then the 5th age was a further 169 years. I mean, to use a real world comparison, there's barely any notion of fear of western civilisation descending into all out warfare even with various political unrest and conflicts in the middle east etc and its only been 70 years since we were last in a mess of war and still have people alive who lived through it. Gielinorians haven't know all out major warfare for 2169 years and there's no-one milling around in general society who was really there.
Then if we look exclusively at the 'big 4'
Bandos - God is dead, followers are essentially in retreat with many going off to follow Zanik. They don't really have much in the way of a civilisation anyway, so theres not much reason for them to be presented as being organised and preparing for stuff.
Armadyl - Pretty much no followers on Gielinor just the aviansie he brought with him when he returned really who will be located in the sky citadels and based on how the ones we use for clans pan out they don't really have cause to be leaving them to prepare.
Zamorak - All his core forces have been given tasks or called to his side. In terms of general people around the world he doesn't have much of a following just the Kinshra who don;t really do a lot and a few fanatical monks busy preaching. There's not exactly a lot in terms of followers to be seen doing anything.
Saradomin - Pretty much everyone left on Gielinor who is civilised follows Saradomin and with the gods return they just saw him own Zamorak and gain a butt load of power. The vast majority of ordinary Gielinorians who follow him wouldn't really see a reason to be scared. Their god has proven he is powerful and they already have nice big armies and fortified cities built up, all they need do if its hits the fan is shut the gates and hunker down.
I just don't think the story as a whole of this developing conflict/godwars 2.0 is at a point where it really makes sense for there to be much in the way of visible factions preparing stuff going on. The concept is nice and I have nothing against it at all; just doesn't seem like the right time for it to be happening yet. There's other developments that would make sense at this time - unrest and break down of what little Bandosian society there is, the beginning emergence of camps, cults or churches towards Arma and Zamorak now the Saradominist sheeple have been exposed to the reality of other deities existing etc.
Just for me, not really enough occurring for it make sense for there to be roaming faction militia bands trying to horde goods and skirmishing.
You mention that we don't have much fear of returning to global war after only 70 years. But we had stockpiling between the US and USSR for years after that war because they were afraid of the threat, and I'm pretty sure if someone viewed as a great enemy for many people like Hitler returned with the power he had before the war ended then the stockpiling would commence again.
As far as the followers, its kind of my point that they don't really "do" much at the moment. We see how the citadels work for clans, but we don't really see much variation. There is some metal, some food (that apparently comes from nowhere so possibly delivered to the citadel from below), 1 type of tree. It seems like to get specific types of materials the aviansies would still need to go to the surface. Bandos is dead but whether some follow Zanik (which is only a chance, she can also die) there are still large numbers of Bandosians on Gielinor that don't, and they already have a hierarchy so I don't see their civilizations just collapsing. Saradominists have ruled much of Gielinor for a long time, but still they are afraid of Zamorakians, and I wouldn't be surprised that they want to gather more supplies in order to try to take as much of Gielinor as possible and counter the others.
I guess I just see roaming militias as the step before cults start really solidifying. To me, full organization comes after the roving bands go across, as those bands might start setting up outposts and further civilizations. Although I might include those ideas later if there's a Runelabs contest that I think fits them better.