WotC are hoping that DnDnext will unite D&D players from all editions; I believe that even creating an absolutely amazing gold-standard set of rules that cater for players of all styles and editions won't be enough on its own to bring people together. These forums show clearly just how far 5e will have to stretch to please everyone, and even once 5e is released there'll be a period of time before players are able to really get the most out of it. Players will only most likely see other playing styles when they attend conferences or official events, so it will take time for word to spread.
My idea is this: to support and accelerate the process of bringing players together, create an area on the WotC website called something like "D&D University". A common maxim for writers is "Show, don't tell" - D&D University should do precisely that - show people how flexible 5e is, how it can accomodate different play styles, show players from all editions sat round a table playing the same game, and show them having fun together. Demonstrate how the modular nature of the game can be used to craft your own version of D&D; demonstrate that administration of the modular system doesn't increase rule management complexity unduly. Show players rolling characters; show DMs creating monsters - and so on, and so forth.
WotC have produced some great podcasts and D&D videos over the last few years, including the ones involving the Penny Arcade and Robot Chicken crews, so it's something they know how to do. Videos or podcasts should include experienced players (perhaps WotC staff) as well as celebrities, so that viewers are able to see different aspects of play (low level, high level, gritty fantasy, heroic fantasy, etc.). Some videos of D&D Encounters / Lair Assault would be good, too - assuming these exist in a similar form for 5e.
D&D University should be about showcasing 5e, but it shouldn't be just about that. D&D University should help players and DMs alike to improve and to broaden their horizons, by showing them styles or techniques they might not have seen, and getting them more involved in the game. There's some great material on the WotC site already to start it off, notably the fantastic "DM Experience" articles by Chris Perkins. His DM commentaries on the Robot Chicken videos were interesting and thought-provoking.
In summary, D&D U should:
- Demonstrate the flexibility of 5e
- Show that players of different styles and editions can play together
- Help players and DMs alike to improve and get more out of their game, through example
- Inspire and entertain viewers / listeners
- Keep people returning to the site week after week to learn more
I think something like D&D U would help to build bridges in the community, and I think if done well, it would help with 5e adoption. I'd hope that WotC would be able to launch it alongside the launch of 5e, but (NDA permitting) if WotC were able to produce some carefully edited / screened gameplay videos some time beforehand, I think it'd help their cause enormously.