Google’s Gary Illyes announced they plan on releasing a separate mobile search index, which will become the primary one. On the heals of “mobilegedon” which started to prioritize mobile results, this move is not surprising. What is surprising with this announcement is the concept of two separate indexes, where the desktop index will not be as up-to-date as the mobile index.
According to Search Engine Land, the change will be within months, Google to divide its index, giving mobile users better & fresher content. Google first 
announced that it was experimenting with the idea last year at SMX East. Since that time, Google’s definitively decided that a mobile index makes business sense and is moving forward with the concept.
It’s still unclear on how the index will work. It’s hard to believe that Google would separate the two permanently, given their drive to always simplify things. My guess is that the separation is part of the initial transition to the new index across the board. In addition, “out-of-date” for desktop is not defined by days, weeks, or months.
What does this mean for small and midsize companies? If your website is not mobile friendly, you’re about to get left in the dust. This also could spell disaster for companies that have invested in desktop SEO for a decade, only to be slow to transition to mobile and could lose it all. If you pull up your website on your phone and think, yikes call me. If you want to see how Google sees your site, use their tool: https://testmysite.thinkwithgoogle.com/
Overall, this change will be a fundamental shift that should be seen as a concept not a singular. All future changes (pending it goes well, and Google makes more revenue) will be moves to support and promote mobile results.
