Yeah, my personal outline of a sort of "4e-inspired" system is similar. I don't kid myself that I'm going to, or really capable of, writing a whole RPG that would add a whole lot to what is out there now, but its fun to create an outline anyway. My idea is to replace everything with 'boons'. You just play though the narrative and you acquire whatever you get based on the action. Level increases are then based on how many boons you have (IE if you have 10 boons maybe that makes you level 5 or whatever). You could adjust that based on the sort of fiction you want. HP and such can be based on level and basically all that core stuff could be pretty much right out of 4e, though I have some tweaks in mind.
Classes would still exist, they could define your HP progression and starting boons (which would be mostly your proficiencies and such plus some basic class mechanics). You'd just create a new class/subclass for every distinct enough archetype that would matter (So rangers can just be fighters that trade 'heavy armor proficiency' for 'tracking' etc). 4e/DDN/13a style background/theme/whatever would of course be perfectly feasible as well. ALL of these would however just act as packages of stuff, ways to make the DM and player's job of visualizing and constructing the character easier.
Clearly there would be some distinct differences in details of implementation between this and DDN or 4e, but I think you could get close to the same sorts of results. Different sets of boons would be an easy enough thing to develop for different styles of play, and adjusting some of the core rules (healing etc) wouldn't be drastically hard either, so you could support more than one type of play, genre, etc. I could even see different class and leveling rules for really distinct things (like a cosmic horror game could do away entirely with hit point progression by just saying "well, you never actually level up, no matter what boons you get").