Optimization techniques are highly tuned to the dominant search engines in the target market. The search engines' market shares vary from market to market, as does competition. In 2003, Danny Sullivan stated that Google represented about 75% of all searches.[63] In markets outside the United States, Google's share is often larger, and Google remains the dominant search engine worldwide as of 2007.[64] As of 2006, Google had an 85–90% market share in Germany.[65] While there were hundreds of SEO firms in the US at that time, there were only about five in Germany.[65] As of June 2008, the marketshare of Google in the UK was close to 90% according to Hitwise.[66] That market share is achieved in a number of countries.
You can also use organic to increase audience engagement with your content. For example, let’s say you’re a ticketing website for sporting events and you know that some of your followers are rugby fanatics. If you have a new blog interviewing Dylan Hartley (current England captain), then it makes sense to personally contact them (or at least key influencers) via their preferred social network and tell them about the blog, and ask them to comment/share. It’s personal and increases the chance they’ll see/read your content.

And the other way to do that is really through status updates, very short simple things to start engaging your audience, talk about the things you’re learning in the business world. And when it comes to what that strategy can look like, what I always recommend is you sit down with whoever you think are going to be your thought leaders and figure out what part of the business do they really want to position themselves as a thought leader about.
Optimize for opt-ins. Make sure you lead to something more than your content. What this means is that when people read your content, they must know where to go next. This may come in the form of a call to action or your offering of additional content, appearing perhaps as a PDF. Growing organic traffic is important, but it doesn’t matter if you are not converting those viewer into leads. Your business doesn’t pay its bills using raw traffic.
Companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the Wall Street Journal reported on a company, Traffic Power, which allegedly used high-risk techniques and failed to disclose those risks to its clients.[15] Wired magazine reported that the same company sued blogger and SEO Aaron Wall for writing about the ban.[16] Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.[17]
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.
I would also advise to continue doing what works. If something you have rolled out generates great traffic and links bring out a new version of the content, for example the 2012 version worked effectively bring out the 2013 version of the content. Another effective strategy is to make the piece of content into an evergreen article which you add to over time so it is always up to date.

Organic is what people are looking for; the rest of these simply put things in front of people who may or may not be seeking what you offer. We know that approximately X number of people are looking for Y every day. So if we can get on front of those people, we have a much greater opportunity to create long-term relationships and increase our overall ROI.