So, what I take from your answers is that while the industry needs D&D, D&D does not need the industry. I most honestly believe that in today's world this is categorically wrong.
My guess is that this transition is well in progress, and is behind a lot of what has been going on with the brand lately. I don't think D&D is going away or anything crazy like that, but I think a lot of it is going to go behind an online paywall, and eventually I think a great deal of D&D play is going to take place online.
--Erik
and eventually I think a great deal of D&D play is going to take place online.
The thing is that D&D to remain relevant as a brand needs constant retailer presence. Perhaps, the minimum of what it needs to achieve that is a monthly magazine in paper format like what Dungeon and Dragon used to be.
I don't know that the game needs constant brick and mortar retail presence, at least in the form we've grown used to. Think about WoW. You've got the starter disk boxes and prepaid reload cards, that's about it (not counting themed swag that doesnt really affect the game, but keeps the brand publicized, D&D could use more of that too, but its another issue).
If they intend to keep the brand name of Warcraft relevant after WoW has been eclipsed, well at that point they will have to support this by various means.
I wonder how much actually constitutes "a great deal", however.
I can safely say that throughout my entire lifespan, 0% of my D&D will be played online. If I can't get people to sit down at a table and play D&D with me, we'll play Savage Worlds or CoC or Traveller or something else. And if the day comes that I can't get anybody to sit down at a table and play a role playing game with me, I'll just play a minis wargame or a boardgame instead. And if the day comes when tables themselves are abolished and no one will ever sit down with me to play anything, then I'll just do something else with my time.
But I refuse to play D&D or any other tabletop game online. I'll play in my gf's freeform forum game and I'll play WoW or the equivalent, but I won't take something that is made of reality and trade it for something made of electrons. If it's already intended to be made of electrons, then fine. But I'm not trading down. That would be like using Skype with someone who was in the same room with you... just turn around and look at them! It doesn't make any sense.
Over on Fear the Boot, they did an interview with Ryan Dancey some time ago. Dancey talked about the market research WOTC did going into 3e and one of things that stuck out was that D&D was largely (at the time anyway) a suburban thing. People, like me, out in the country lack the population base to get a group together and people who live in the city have too many other options competing for their time.
The other big demographic bubble was high school and college ages since these correlate to people having large amounts of free time and have a fairly easy time of finding like minded individuals. Imagine trying to go out and rebuild an entirely new group of gamers of people in their 30's or 40's from your co-workers.
Sure, some people can do that, but, most can't.
The online option breaks that down. Now, you can find a game and a group, that fits with your tastes and, just as importantly, fits with your schedule.
That opens D&D (and RPG's) up to entirely new market areas that have traditionally been pretty closed. I can easily see why RPG companies want to get into a more online approach. It makes too much economic sense not to.
Sucks for those who don't want online stuff in their RPG's though.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.