A good vision statement should clearly outline where your venture is going in the next five years or so ...
Why five years? Why not?! Five years is a traditional choice when it comes to a business planning time frame ... not too far away, yet not too close either. Where do you think your venture is going to be in five years ... what's your vision of your five-year future? Not firm and fixed about five years, but a good starting point.
Here's a seed concept for writing your vision statement: "In the next five years, we will change the way someone does something."
Who is the someone (your target market segment)? What will they do differently, and why will they change (because of your value proposition)?
Example: "In the next five years, the Broadway Pizza Parlor chain of restaurants will change where gourmet foodies in Arizona go to find the very best deep-dish pizza."
A good vision statement should be purposeful, consistent, unique, and clear.
Also, See: Vision Rules of Thumb