The Google Mobile Friendly Update (GMFU) launched on April 21.  This update will prioritize search results for mobile friendly sites.  In other words, if your site is not mobile friendly, you could see a drop in search originated web traffic.
That being said, this only affects Mobile search results.  So if your target audience is still finding you from a Desktop browser, you might not be affected.
Of course, in this day and age, web traffic is increasingly mobile and organizations that are not focused on mobile access to their digital assets will be increasingly marginalized.
One of my favorite Tech Sector Analysts, Ben Thompson, wrote a fantastic post on web traffic, mobile access and the increasing role played by Facebook.  Definitely worth a read.
To find out more about the GMFU and what it might mean for your site, check out this very helpful FAQ from