I think it would turn out like EVE online. Every entertaining story like this you hear about, there are 100,000 man hours of tedious boredom behind it.
I had a lot of fun playing the Arma Mod, enough that it justified the .
It can get tedious when you're searching for food or trying to meet up with friends from distant parts of the map. The real fun is in the interactions with other players, which can happen more or less depending on your playing style.
That looks fun but I'm impatient: with a little work I can get a few of these interactions from just one session on this website. It doesn't cost anything either, but you'll notice there's a donate button now on the homepage so consider that...