I voted no core setting, that way the assassin prc will not have one guild's entrance exam written into the core requirements, spell names will not be named after a guy who existed in one world and they can feel free to slay whatever sacred cows they see fit. Greyhawk can have all these things, in it's own books. I'm all for supporting the setting, something they have failed to do in 3.x as far as I'm concerned.
in the core, let the cleric's go without gods, I always liked the option they presented of not having one. just have it written as cleric's get two domains, player choice with the allignment based ones requiring that you be that alignment. no pantheon required, saves a few pages of text space for more feats or better rule descriptions. in the fr, greyhawk, ebberon, Enter random setting book here, it can be written that clerics are more confined, needing a god to fuel their power. It adds flavor in fact. leave flavor out of the core.
I want more options and fewer presets. In my opinion this is more easily accomplished without a core setting and allows the writers more creative freedom for the generic suppliments. Knight protector of the great kingdom, eye of grummsh and all the other greyhawk specific prc's never get used in my games and have stopped me from wanting to buy any of the "generic" Wotc suppliments for about three years now. it's not generic if it's 35% greyhawk content.
the less setting info you put in the core, the more likely you are to sell setting books to new players and dm's. in stead of one splatbook that is "generic/greyhawk" you can have one for classes like cavalier, swashbuckler, samurai, and other concepts that are easily worked into any game or left out as you see fit and at some point another one, specific for each setting.
For greyhawk, come out with a campaign setting (for geography, pantheons and power groups, npc stat blocks), players guide (classes, races and cool gear/spells from that setting). If the campaign setting books didn't have to have all that player information in them, they'd be more useful to dm's and more would buy them. players would buy the players guide (at least the ones that currently buy the splatbooks would) for the setting that their gm had purchased. If your campaign setting book was comprehensive enough ie around 400+pages, you don't need setting support other then adventures after that and you can move on to new settings and put out more generic suppliments.
A setting like FR, with it's incredible vastness might require more then a single setting book and any new settings undoubtedly would require some after release tweaking through suppliments but there's no reason a setting atlas for all the older settings couldn't sell if enough usable (ie integratable) content was worked in. planescape as a "atlas of the planes" DM book with the players guide having the planar playable races and faction prc's, Darksun setting being the "how to play in a desert" rules book. the players guide including the psionics rules and having prc's and powers to support those rules. Birthright having rules for political minded campaigns. the players guide covering mass combat. that's what I want
sorry, got off topic, my bad. it's just that I'd rather see settings get integrated into suppliments rather then be tossed to the side. The default setting failed as a concept in my opinion but I hope they do not drop Greyhawk entirely.
edit: clarifiying concepts and trying to correct grammar
, writing in 2 minute chunks at work does not help such things.