What I find particularly interesting about this thread is that there are very few new or innovative ideas that aren't already present in any number of 3rd party products. It seems that there is a majority of folks here who want nothing more than their personal game to be made canon. Which, in my opinion, is no more desireable than vanilla D&D.
In the interest of contributing to this thread further; and being fully aware that this is my personal view and no more valid or desireable than anyone elses; I would like to see:
* Classes should never grant static class abilities. Every class should have access to a range of abilities throughout their career. Like no two fighters need be the same, because of feat selection, no two rogues, rangers, or clerics need be the same.
* The magic system from Thieves' World (with tweaks)
* MDT, Defense, Reputation
* Options which account for low magic/poor magic settings. ie. Reliance on magical equipment not a necessity, and how those characters would scale with the default setting.
* Remove the assumption that the typical character career spans 1 to 20 + Epic. This ties in with my previous requests.
Currently, I run a game where everyone begins at 5th level, and experience is gained at 1/10th the rate. This means that characters are going to be stuck at certain levels for a very long time. The maximum level of the campaign may get no higher than 9th or so, so I've adjusted my classes so that they are templates providing a number of choices for players.
Several of my ideas, could be easily accomodated now, if the Open Gaming Foundation or other 3rd party designed a method to measure Combat Grittiness, Magic, Monsters etc. If you want Low Magic, Gritty Combat, you should be able to identify those products readily. What High Magic, Over the Top Action, then look for products with those ratings.
But my number one request above everything else; even if there never will be a 4e; would be a true Dungeon Master's Guide that contains nuts and bolts GURPS like detail of how to design races, feats, classes, monsters, spells, or just about everything that has been pregenerated by the authors.