If I understand the question, you are asking how your business location might affect your overall ranking for your main keywords.
The days of everyone in a country, e.g., the U.S., seeing the same SERP's regardless of location are gone ... or going. Google for example has indicated that they want to try and use all the information at their disposal to serve the best possible set of results for any searcher. Note I said searcher, not search query.
So if Google as a search history on you, and knowing your IP (which tells them your general location), they are going to try and serve results that reflect your past queries as well as your location.
Every business has to think about what this means for them, but what I can say is, it WILL mean something for many -- if not most -- businesses. And that is especially true if your business has a bricks and mortar component or focus.
I also would venture a guess that the further you are down in the rankings, the more of an effect it will have, simply because there are more locally relevant listings with the potential to slip in above your listing in the SERP's.