Can Google stay on top of the web?

A recent article in BusinessWeek discussed how Google is dealing with Bing, Facebook, Twitter, and other upstarts taking some of their market share. They are actively combating these upstarts by constantly improving their product and offering new and improved features. Google currently has slightly more than 70% of the market share, with their closest competitor only claiming 18% of the market. Google is smart to continue improving their product despite their enormous claim on the market. If Google lets down their guard for even a moment they could lose it all to any one of the upstarts nipping at their heels.