Google has recently stated that responsive website design is needed by April 21st due to Google’s algorithm update. Google will be using mobile-friendliness as a ranking signal that could impact your website and whether it ranks higher or lower in the search results. Google's Zineb Ait Bahajji is quoted saying, "the upcoming mobile-friendly algorithm will impact more sites than their Panda or Penguin algorithms" at SMX Munich.
It is quite amazing where we have come from since 2012 with regards to mobile. According to WebDam in 2015, mobile marketing in the US will generate $400 billion compared to $139 billion. Also an article on Search Engine Land says, "50% of all searches done on Google are on mobile devices."
Before you start worrying, you can test your website on Google’s Mobile-Friendly Test to see how your responsive website design measures up. In addition, there are many resources-such as how to avoid common mistakes.
At the end of the day you can only applaud Google for making companies follow responsive website design because it is in fact providing a better user experience for those on mobile devices.