There was AMA interview with David Braben on Reddit:
http://www.reddit.com/r/IAmA/comments/15od2s/i_am_david_braben_cocreator_of_elite_creator_of/
Here are some quotes from there:
Q: After numerous mishaps and false starts, I have grown extremely averse to multiplayer as a whole, outside of a private LAN. In my current situation, such LAN parties are out of the question, unless it's Starcraft... which I detest. I realize that Multiplayer is a big financial incentive, but do you intend to apply the same amount of effort and energy into the Singleplayer experience?
A: (David Braben, Dec 31 2012) A hard one to answer.
Almost all of the game world work applies to both single and multiplayer. Exploration is very nearly a single player experience, though much of the fun comes from the fact of the multiplayer world. We do not see these as separate experiences.
Q: Will the evolving universe that Elite: Dangerous is set in make it less enjoyable to play in say 20 years time? As minable resources become more scarce and inflation makes it harder for newcomers to the game. Or will there to be a static non-evolving universe for the single-player mode that will live on?
A: (Michael Brookes, Dec 30 2012) Space is big

Most of the galaxy is unexplored when the game begins and there are plenty of resources to be discovered. There will also be an offline single player mode.
Q: I still play the original Elite on my laptop on the way to work. Will I be able to play 'Elite: Dangerous' in a single player mode without any connection to the net? Thanks.
A: (David Braben, Dec 30 2012)
Yes, though you will lose the richness of multiplayer.