More eyes on your website are all well and good, but if you can’t get them to interact, you lose. Engagement is what’s going to facilitate the conversion that you want. When users become invested in your content, they keep coming back, and they become the fuel for your sales funnels. So what is a “rich content experience?” Here’s what I recommend. Be intentional.  Most people pump out content because they heard it’s the right thing to do. No rhyme. No reason. That’s a mistake. Every piece of content should serve a goal.
I think for agencies as far as how we appear in organic search ourselves, we are definitely going to need to leverage all 3 of the solutions you talk about and agencies who haven't branded their products/services are going to have to do that and are going to have to also employ branding strategies. In addition, we have to optimize for other search ares like you say in your point #2 and we must look at optimizing existing content for voice search and answers/featured snippets like you say in point #3.
Although it may have changed slightly since BrightEdge published its report last year, the data still seem to hold true. Organic is simply better for delivering relevant traffic. The only channel that performs better in some capacities is paid search ads, but that is only for conversions, not overall traffic delivery (Paid Search only accounted for 10 percent of overall total traffic).