The exercise I think you should consider is examining what you're NOT going to do. Don't reduce this to a BS exercise interview question of "What are my weaknesses" and answering "working too hard."
Give it a real go: figure out what requests you're going to answer NO to.
Look, I don't mean to be harsh, but is really, really easy to say YES. It's our default setting. Especially if you're in sales.
But if you don't figure out how to say NO, then delivering is extraordinarily difficult.
Start small: say no to clients that are too big (or too small). Set a threshold. Limit the number of backends you have to interface to. Limit it to non-realtime.
But try to bound the product to something you CAN deliver.
While I agree that it's a good idea to start with some limits, with a business model like this (few customers, mucho $$/customer), it's probably better to let the first few customers dictate what to start out with. Of course the early product can't be everything to everyone, but it can be everything to one client! Then it's a base to build off of, finding the next client with similar needs and adding the diff to the product base. This way, as the diversity of customers grows, the product will grow with the business and open new opportunities.
Having said that, I'm curious to know what you think your first customers will be like (size, industry, etc).
