Here is a recap of where we are in this discussion: Business plans formalize an understanding of the task with appropriate analysis leading to a plan_of_action. Not all business plans are for profit motives. Business plans are for an enterprise effort and not focused on disciplines/departments, e.g. Marketing plan, sales plan, HR plan, supply chain plan, etc. Business plans are a great vehicle to build a team effort. Plans can be utilized for formalizing metrics relative to achieving goals and performance measurements. Some complex plans might include a Project Management professional. There are internal and external audiences for business plans. Most external focused plans are for outside funding of projects. Be mindful of the 'tone' the plan projects to the reader. Tone refers to the impression a person gets from reading the plan; a subliminal feeling about the plan.
Another consideration. Should the business plan be a document that is focused on selling an idea for a product or service? For many years I worked in a company that did not want anything in a business plan that could be construed as showing a bias towards or against a project. The mantra was to only present facts in the business plan. The Operations Research Department was there to review the analysis as being unbiased. To handle the "what if" scenarios or sensitivity analysis we prepared a supplemental analysis documents which were mostly financial oriented. Personally, I like a factual approach and use the presentation of the final document to point out the conservative aspects of the content.