Google launched the Knowledge Graph just last week and SEO webmasters are worried about the effect of displaying direct answers along with search results - will it decrease traffic to your website?

The answer at the moment is no. While Google Knowledge gives a better search experience by providing the answer to the search query on the results page itself and providing several alternatives to refine the query to the exact meaning of the search, it shouldn't interfere with internet marketers who deal with search engine optimization to promote their websites.

The reason for that is not only the location of the Knowledge Graph results (at the middle right part of the search results) but also the fact that organic search results have been around for quiet a while and as Google does more and more to improve the quality of these results, the users use them more than any other alternative including sponsored ads.

In addition to that, websites often provide an added value to the visitor, something in addition to the information or answer only which is relevant to the search query, perhaps we are used to be offered something while browsing a website.

The bottom line is that Google's knowledge graph is definitely an improvement to the way we search, nevertheless information is not the sole property of Google and can never be, this is why SEO will not die, well not anytime soon that is.
If there's anything webmasters should be concerned about is the growth of Facebook and other social media as targeted traffic sources and the need to be there as it happens which is not obvious. In addition going mobile is also a must in the age of smart phones and tablets and a well optimized site can help webmasters convert better and show good results out of mobile traffic.