I'd disagree that you could drop the non-human races from the core rules. At least if this is supposed to be a "bridge" product - I figure a lot of those new to the game are going to be coming from, as others have said, having seen films or read books such as Harry Potter and Lord of the Rings. I know I'd be ticked if I picked it up and found I couldn't play Gimli or Merry.
Anyhow, here's what I'd put in it ...
- limited levels - 7th or 8th max, enough to get some good stuff (multiple attacks for fighters, 4th level spells for clerics and wizards).
- just the four basic classes - fighter, cleric, wizard and rogue, but keep multiclassing.
- races - human, dwarf, elf and halfling.
- skills - trimmed down list of skills, each of the four classes given a short list of skills that can be taken, any selected skill has a rank of class level or 1/2 that if the skill would be cross class in the PHB. Skills selected at 1st level gain +3 ranks. Intelligence affects number of skills that can be taken. Character stuck with skills selected when first taking that class.
- feats - a short list of feats to choose from for character level, and a preselected list for the fighter and wizard
- combat - much simplified, include a very basic version of attacks of opportunity (something like cast spells or drink a potion in melee, suffer an AoO). No requirement for minatures at all.
- monsters stats simplified as much as possible
Definitely an appendix or two, one to break down the differences between this product and the PHB/DMG/MM so those who start out with this product can see where the difference between the two are, and a second appendix to help convert PHB based products back to this product's stats, so less need to support a separate line of products.
The idea being to keep the mechanics as close as possible, so if one decides to stay with the basic set, one could then pick up the PHB for the additional level progressions, as well as more feats and spells, and make use of PHB based material such as modules, campaign settings etc.
Oh, and lots of examples of play - including such things as the social skills (diplomacy, etc) so as to give the new player an idea of how they fit into role playing without necessarily substituting for it.