I got an email from the Google Webmaster Tools Team in relation to one of my old sites.
Google systems have tested 204 pages from your site and found that 99% of them have critical mobile usability errors. The errors on these 202 pages severely affect how mobile users are able to experience your website. These pages will not be seen as mobile-friendly by Google Search, and will therefore be displayed and ranked appropriately for smartphone users.
Now I have to update this old site. I feel it is a good time to implement some current technologies like angular.js and jquery with it and maybe some others. But this is really a tipping point in the supremacy of sites being ready for mobile devices above normal computers and laptops.
CMS Wire has more detail here about the change.
It’s possible to test a site for mobile friendliness using this link.