So Siri is for consumer devices and Watson is going to be for businesses. I dont think they are going to be killing each other since they are targeting different markets.
I asked Siri "Did Michigan win its bowl game?" and it gave me the right answer and said "Michigan lost to Kansas state in the Buffalo Wild Wings Bowl.
Wolfram Alpha, with the same query, just gave me information about the state of Michigan.
Bing gave me search results about Michigan Football, and Google's top results were an article about the actual bowl game. I don't have an Android phone to try Google Now.
I'd like to see that happen if only to push Google to open a Google Now API. To me this sounds like Wolfram Alpha for business more than Siri or Google Now though.