Google's Gary Illyes also said yesterday during the SMX mobile-first panel that while this whole mobile-first index is up in the air, they may decide to "smear" some desktop signals into the mobile-first index. That means, they still might use some signals they collect in their desktop first crawl after they launch their mobile-first index.
Why? Well, Google keeps saying how there is less links and less content on mobile sites than on desktop sites. A big concern for Google is since there are less links, PageRank signals can seriously fluctuate and their rankings won't be quality neutral on launch.
In short, mobile sites have less links than their desktop counterparts and if Google crawls the web with a mobile-first viewpoint, Google will find less links.
So similar to how Google currently uses mobile signals for their desktop index they might just flip it and use some desktop signals within their mobile index. This of course is still just hypotheticals since we have a while until this rolls out but this is the current challenge for Google.
Here are some tweets from the panel on this:
@methode: we could smear some of desktop signal to make up for lack of content and links. #smx
— brysonmeunier (@brysonmeunier) June 13, 2017
Google may smear desktop signals for mobile first index. #smx
— Barry Schwartz (@rustybrick) June 13, 2017
Forum discussion at Twitter.
