Most people, especially companies, are very reluctant to adapt to an open source model themselves. Why would someone put so much money, time and resources into a project and then give it all away for free? What will stop one's competitors from taking advantage of all their hard work, for nothing in return? Well, you can make both of these things work for you.
January 1998, Netscape Navigator has already lost it's dominance of the browser market to Internet Explorer. The decision was taken to open source the project. In the coming years, the Mozilla Foundation releases Firefox, the single biggest threat to the now omnipotent browser from Microsoft. And this is not the only consequence. The SSL protocol, first introduced by Netscape, is made into a standard and chosen as the de-facto way of establishing secure connections. This is a good example of how open source made this product a bigger success than it ever was while being closed-source.
Open sourcing your product should be the consequence of carefully examining the pros and cons of doing so, and not trying to fool yourself on the way. If you think of "open-source" as the solution to getting your work done for free, you are in for a rude awakening. Going open source should be an effort to build a community around your idea and making it an integral part of it. This also means that you will have to invest a lot of resources in making this happen. Your code is probably not clear enough for new developers to understand. Documentation is probably lacking or completely missing. You will now have to coordinate not only your own developers but also a whole community. And keep in mind that if they don't like how you are managing things, they might as well just fork the project or abandon it altogether.