Of course they should. I wouldn't mind a Worlds of Adventure, but I'd expect to be something like the Dungeon Survival Guide: e.g.: all art and fluff and intro material.
I'd like a DS hardcover that introduced Athas and gave some quick rules and maybe had an intro adventure. I wouldn't want something hyper-detailed like the 3e FRCS, but maybe something to help people get a handle on it.
For
Race, you'd have DS's twisted take on the fantasy archetypes. Cannibal halflings and sprinting elves and muls, yes indeedie! Each has their own "lands," and they all come together in a big central city in an oasis under the watchful auspices of a Sorcerer King.
For
Class, you'd have some DS-exclusive takes on it. With the powers system, I think it'd be easy to integrate new and existing classes, so we'll take the Galdiator and the Templar and the Defiler and the Preserver and the Psion and the Psychic Warrior, and the Rogue and the Bard, and the Druid and the Elemental Cleric. They should be built from the ground up as Athasian classes, rather than retconned, but it shouldn't be too hard to give them come core options, too. So the Athasian rogue is still a striker, just one who dabbles in Assassination talents. The Athasian Gladiator is (maybe) a Defender, but the taunt and the net and the unusual tactics aren't out of place. The Druid would almost be a Leader in Athas, who is able to enhance the world around them. Defilers should have their own unique ability set that saps the life from around them to cast, while preservers should have their own unique ability set that saps their own life to cast.
For
Feel, we'd basically establish a hardscabble postapocaylptic world. Monsters, bugs, terrain rules, a few neato places with great gut-punch possibility described in brief paragraphs: "The Silt Sea, The Free City, The Salt Barrens," whatever. We introduce the most important Sorcerer King for the PC's (the one who rules over the city-state that they live in).
For
Setting, we describe the city the PC's will be headquartered in, establish a few thematic NPC plots, and let everyone go wild.
I'm a fan of DS (though not as obsessive as I am at planescape!), it's a very good setting, and as long as WotC uses a light touch (and not 3e's attempt to square-peg/round-hole it) they might not screw with it too much.
