You mean the entire Zone as one single gigantic map, no level-changers?
Hmm. Might have to wait for somewhat more powerful hardware for that one.
But it would certainly make a big difference. Even if it had load-points, a bit like HL2 where there is no distance between where you are when the load starts and when it ends. In Stalker you go into a level-changer and find yourself miles down the road when it loads, but in HL2 you hadn't moved and just continued down the road as you were.
That would mean bringing in new maps to link all the others together, just basically wilderness maps maybe with a few hordes of mutants hanging around for target practice on the way to wherever you're going.
Would be interesting, but a whole lot of work for some level-builders.
.