I'm not sure that selling Dungeons and Dragons as "entertainment" instead of "hobby" ...is going to work out quite the same as with Magic.
I am by no means qualified to make predictions on sales... I think the idea is not to turn D&D from hobby to entertainment, but to make it
also possible as entertainment. The difference is that "hobby" requires a certain continuity, while "entertainment" is casual, requires little planning ahead, and smaller times. I believe that going to the theatre, watching a movie on DVD, play a videogame, do karaoke or a night with games of cards are good examples of what they're trying to make D&D compete against.
And I have to say that from my personal point of view, that would totally rock! I have been myself a hobbyist of D&D during the 3e era, buying a small set of sourcebooks, DMing some games and playing in others, writing/preparing adventures and homebrew settings... But nowadays it's too much work to do it too often, and my former co-gamers basically all moved on, had kids, got into other hobbies etc. They say they would still like to play
but none is willing to DM unless it's much less effort than before, and even can't guarantee to play two times in a row.
I believe WotC knows there are lots of previous gamers in this situation, missing the fun of a good D&D night at least now and then, plus other people who simply don't like doing stuff that requires more than one evening. The point is, making D&D work for these people, in absolutely no way would undermine how it works for those who want the whole D&D experience of long campaigns, designing homebrew settings, tinker with house rules and monster design etc.
How is your shelf of non-OGL D&D books useless? Can you not use them in your game?
I think he's a designer, so he meant he can't use any non-core material as a start for further design ideas.