Forget the book publishing aspect for a minute - and think about general points that apply to any business venture:
1) What specific experience do you have of book publishing?
2) What do you offer that would make you stand out from the competition? Are you cheaper? Do you add value in some other way?
3) What is the distribution mechanisms that you have?
4) How do you play to pay yourself and any staff for at least a year without income or very limited income?