How can I best predict the potential return of launching a new software for sell? I'm about to enter in a "joint-venture" with a software company: They have already sold their software for a time and now they are interested to incorporate some of my ideas, which would require them to change their software substantially. So before they want to begin with this whole project, they would like to see some proof of that they will get more money back than invested to develop my idea.
How can I best do that? Isn't it just for me to, as detailed as possible and as realistic as possible, explain the whole concept and that because of X quality of this developed product there are many users who would like to purchase it?