Yes, you have to build the shelf life of the company into this. One model I have seen a Seattle investor use is to assume a shelf life of 12-15 years at best. But if you can return invested capital every 2-4 years, you have a good run. And if someone offers to take you out, you can measure your opportunity cost against the offer, i.e. you can determine whether the buyout makes more sense than running the company through its natural life cycle.