Hard to say Rob, I don't think that even Google could answer that but I have been thinking about it as it does form a big part of my job.
The first thing I have noticed is that, since the Hummingbird update, the natural search results have been somewhat "volatile" compared to the relative stability that you could once achieve. For example, the main keywords relating to my day-job can bring my website up in the top 3 positions one day, and then just 3 or 4 days later I can be clinging on to the bottom of the first page, and then back again a few days later. My competitors seem to be having the same problem and a worse time of it if anything. My guess is that it is due to the way Google processes short phrase searches, unable to establish whether the search (or website) is for information or to buy something.
If you rely on a very broad search term, I think the best thing you can do to prepare for this is to follow Google's guidelines and make sure that your website is very informative, even if it is a commercial website or a portfolio. For long term phrases and geographical locations (such as "Personal trainer in Oxford" then you should be benefiting from the Hummingbird changes as long as your site is well optimised.
The second key thing I have noticed much more recently is that the Google Maps and Google Plus pages are changing, they are bound to have a greater impact in the next few months. On Google maps I have noticed that in some cases it doesn't just show the name of a business on a pin but also their products (See this example) and it is now possible to merge existing Google Plus pages with Maps locations, something you should definitely do if you haven't already.
Sticking with Google Plus, it is now separating regular individual profiles and business pages, including a new "My Business" dashboard. This will link with your Analytics page as well as showing you a summary of the reviews for your business including a "Google rating" so my theory is that very soon, Google will announce that their Maps and Business pages on the Plus network will have a greater impact than just websites alone. This makes sense to me as currently people still believe that links are one of the most important factors, leading to website full of spammy links and blog post comments. If they change it to put more focus on "verified business pages" and "customer reviews" then it should reveal a more accurate representation of how good a business is and how worthy their website is of appearing high in the search results.
SEO is hell of a job! People don't actually understand the importance of SEO these days. It can do wonders for you. Im new to it and Im still learning. It is one of the keys to keep an eye on the insights daily.