A member of WebmasterWorld makes a good point - there are some big differences between mobile and desktop SERPs. Mainly, mobile SERPs have had the crap monetized out of them. The prevalence of paid results on mobile SERPs has WebmasterWorld members talking about whether organic mobile traffic is attainable or just a pipe dream.
"Mobile is growing more than ever and will continue to do so. When those people get the Google mobile results more and more, that to me is a losing battle. The effort to reward is virtually a joke," writes MrSavage.
Goodroi writes, "...yes the amount of above the fold space in mobile for organic rankings is shrinking for many keywords. Conceptually it is the same thing that has been happening to desktop organic SERPs for a long time." But there are things that can be done to work around shrinking organic SERPs. Such as diversifying! "Google misleads SEOs on many things but they kinda got it right when they talk about building a good site as if Google wasn't around. Even if I got zero traffic from Google mobile SERPs, I would still want to build high converting, content rich pages that load fast and look great for mobile users that come to my site from the many alternative traffic sources besides Google mobile SERPs," goodroi writes.
Give this one a read for sure, there's a lot of good advice for the discouraged webmaster to take to heart.