I just got this reply from a Ceres Games dev on exploration and level scaling in their game, and it was a fantastic answer:
"We don't have any level scaling planned, everything is hand-placed in our game. Of course, there will be a natural progression based on region - the quests in Sabag-Hirar will be overall a little more difficult since it's the last region you're likely to visit, compared to the quests in Cormac which is the region you're starting in. But we don't want to have a world where just due to the order in which you visit the regions, the monsters are weaker or stronger: closer to civilization, you will find less dangerous areas, while deep in the wilderness you will find more dangerous areas. There will be high level dungeons in Cormac, too - the kind of dungeon you remember as being too hard to attempt now, and will return to tackle after you've gained a couple of levels elsewhere.
What the freedom of our structure allows for is that the player can tackle a questline that is above his level range if he wants to. It's going to be a lot more challenging, but you can attempt it anyway. The Wildlands is one of the most dangerous areas of the game, for example, and its main questline involves plenty of hard battles. Attempting it at low levels would be suicide, but if you really want to you can travel there right away after starting the game.
It's kinda like in Morrowind and its expansions: the Bloodmoon expansion adds a whole new island filled with high level enemies, but the player can go there at any point of the game, even at level 1. He's unlikely to survive, but the option is there. In Fallout 1, there are only three things a player has to do: get the water chip, destroy the military base, confront the Master. It's almost impossible to do only these main quests without doing any of the sidequests, because that will leave you severely underleveled, but if you want to go for a speedrun you can try it.
This is the kind of structurally open non-linearity we want to go for. Instead of rigidly forcing the player to do things in a certain order, we allow the player to jump around and tackle the major questlines in the order he sees fit.
It will be a lot of work for us to balance it properly, but we won't implement any kind of level scaling. That's completely out of the question since it ruins the integrity of the game world and kills some of the fun of exploring and leveling up."