I'm not really aghast at the prospect of Fourth Edition being released this decade, even if I'd prefer otherwise, but there are a few things which would make me smile:
- Keep it within the OGL and broadly compatible with Third Edition. I think the game could use a revamp with everything that Wizards of the Coast has learned about d20 design firmly in mind, but I wouldn't like to see a change on the order of Second Edition to Third unless it were just as spectacular an improvement.
- Maintain a consistent, understandable schedule of releases. Wizards of the Coast should have an understanding of what kind of books are welcomed by their player base as useful additions to the core rules, and their product schedule should leaven these "essential" books with some more experimental products such as the Tome of Battle so as to keep the game fresh even as it otherwise expands in a steady and reliable manner.
- Strengthen the overarching flavour of the core rules. I don't really care whether they hew closely to the original Greyhawk flavour or create something "uniquely Fourth Edition", but the flavour elements of books like Races of Stone and Complete Warrior feel comparatively incoherent, rather than pleasingly generic. It's possible to come up with pleasingly coherent, generic flavour that doesn't seem full of dissonance like the "core rules" flavour currently does.
- Establish a new book-design direction for the core line. Third Edition was a big step up from Second Edition, but I think that if Fourth Edition is to succeed it really needs to establish its own aesthetic identity. That doesn't necessarily mean abandoning "dungeonpunk" or returning to oldschool faux-medieval aesthetics, but it does mean something different from the fake-tome covers and red-brown page frames that dominate Third Edition design. Likewise, Forgotten Realms and Eberron books (if either line are supported to the same extent in Fourth Edition) should establish their own, fresh "look" without dropping everything that was successful about their Third Edition design. For instance, maintaining the tradition of a two-page action spread inside every Eberron book is a good idea, even if Wayne Reynolds doesn't paint them.