Since I'm dming Dark Sun:
An update on races: and I won't accept things like "use goliaths for half giants". That's non sense. I don't want them to force any race. DS is about a dying world with extinted races, not new ones like tieflings on 4e.
Rules for weapons: inferior materials
Rules for armors: 4e edition just says that you change the name and suddenly you can use a "plate" armor in the middle of the desert...
Psionics that aren't just wizards with mana (psi).
Classes to emulate the original set and again don't force new classes like the sorcerer. I want a gladiator, and athasian bard to replace the one in the phb, templars, elemental clerics and defilers and preservers.
Expand rules for environmental hazards.
A new monster manual. I can't just use monster on the first monster manual. I need monster specially designed for dark sun.
And many others not so important like prices in different cities, dehydration an so on.
I'm totally ok with new alien stuffs,I can ban them, but I don't want to redesign things because they say "use dragonborn as drays" just to make dragonborn fit.
I think you got the right ideas. I hope, if setting material is released one day, its more than a book of refluff. I can reluff, you can refluff, everybody can do it for free. The thing is, settings are more than just refluff of the PHB. Some kitchen sink setting can be based on the PHB and works just fine with just a little added flavor. Some dont work that way. If I'm to ban half the PHB and refluff the other half while being forced to discuss the whys of those changes with players new to the setting, its not worth it.
I also dont think the need to balance things out and restrict class bloat is a good excuse. Sure, if you want to make the players options of Darksun 100% compatible with the rest of the product line, it may be problematic. But, if they make a book of options compatible only at the base rules level, it wont be a problem. Sure the system still play mostly the same, but options cant be mined from multiple source because they wont fit. Like in nobody tries to bring PHB races or classes in my Middle-Earth game because they use the Middle-Earth PHB where all options fitting the setting is assembled. The games still plays the same, but it has new rules that are reflected in the class abilities, which makes them a poor fit for more generic setting. I could see something like this:
Players options:
-New
Backgrounds for each city and some for the races of the waste (having a PHB outlander that can gather food easily breaks the theme)
Races of Athas
- Athasian humans (sub-race city dwellers and people of the waste)
- Elfs
- Halfing
- Dwarves (regular and Mul)
- Kreen
- Half-Giant
New Classes
Warrior (fighter)
- Gladiator
- Weapon Master
- Battlemind (1/3 psi caster)
Barbarian
- Slayer (breaks weapon and people)
- Dervish (Dual-wield mobile barb)
- Desert totem (refluffed from the PHB)
Channeler (Warlock-like, people who draws power from other entities)
- Pact of the Sorcerer Kings (City specific invocations)
- Pact of Fire and Smoke (Small modifications to the Fiend warlock could do)
- Pact of Rain (water themed warlock with healing powers)
- Pact of Sand and Dust (Wind and stone based warlock)
Rogue
-Minstrel (Mix Whisper bard and assassin 1/3 caster, you're good)
-Brute (str-based rogue)
-Duelist (arena rogue)
-Raider (desert survival rogue)
Arcanist
- Wizard per PHB, no arcane recovery
- Defilers and Preservers: new rules. Metamagic to all caster, but fueled by Defiling. Risk of Taint (may kill character after a time).
Mystic
- Wilder
- Scion (nobleborn psion)
- Ardent
New rules
- Item breaking
- New travel and survival rules
- New feats: Race feats, wild talents, combat maneuvers
- Spells of the Dying World: adapted spell lists with new spells that interact with some new rules.
That's it for the player part. The rest of the book could be for Dm:
- Brief history
- How to challenge survival, exemple of hazard and travel encounters.
- Bestiary
- Plug-in powers to add to already existing monster to get the Dark sun feel.
That would make for a nice book. Though I understand their fear of splitting the market.