I think this is going to be very very interesting, but not what a lot of people are expecting. I think some key casting decisions are going to be Verity (who actually needs playing by someone like Jenna Louise Coleman) and Sydney Newman (I'd go with Alfred Molina but it needs a bloomin' strong and powerful heavy-weight actor for this).
If anyone is interested, there is a documentary on the 'Edge of Destruction' DVD which pretty much maps out the creative process behind the creation of Doctor Who and will give a great background to the whole story.
I really think Doctor Who is the most successful thing ever made by committee! This story - if done properly - will showcase that