I wonder if they'll seriously consider a 1-book solution for their Core product like many other RPGs do.
As for as boxed product, something that came with the Core Rules Book, Campaign Supplement, and a Dice Set that features 4d6 and percentile dice would probably do the trick.
The real trick to keeping the game easy to pick up and play is to make sure the Core rules favor
intuitive play over
precise play. By that I mean in the Core game don't to be afraid to make various aspects a more free-wheeling system with some guidelines and leave it up to the GM to adjudicate the context. More complex, optional modules (still in the core book) can enforce higher precision rates and thus clearer lines of game balance with less "DM may I?"
For instance, the Skill System - dump mutually exclusive skill silos for more descriptive skills / talents / professions that can easily overlap or allow two different characters two distinct paths to achieve the same outcome. Think more like the implications of the "Profession: Sailor" or "Profession: Rancher" skills in 3rd Edition or what Feats like Alertness were supposed to do in 4E (context sensitive, intuitive talents) and less "Spot, Listen, Search, Move Silently, Hide In Shadows, Use Rope, Knowledge: Goblin Belly Button Lint."
Another example: Maneuvers. In the Basic Core, just have a Fighter pick a style or a Monk pick a Discipline and give the DM guidelines on what kind of effects would cost 1 die vs. 3 dices vs. 6 dice. Then just let the player go nuts as long as he can pay the DM in Martial Damage Dice.
Likewise you can have a very rudimentary and classical spell-list that balances well with this, since every darn supplement in D&D in 3.X seems to expand the Wizard and Cleric Spell lists anyway.
To some extent, I think one of the decisions in the 4th Edition Legend of the Five Rings core rule book is a model to follow: segment the core book logically: core player rules, dm-specific rules, optional expanded rules features. (Just the segmentation model. Goodness, don't follow their skill list model!)
Good candidates for optional expanded Core Rules in the first book: grid combat, expanded spell lists, maneuvers and skill-tricks, specialties. I'm not saying backgrounds shouldn't be an option to remove either, I just think rudimentary character backgrounds should be a default presentation for new players.
- Marty Lund