What will keep on ranking best in the future?

Ok guys (m/f ;-), look at it this way:

Google, to stay the biggest and the best search engine, must deliver top results.

What are top results? -The ones with best CONTENT for the search query.

Sometimes that means product/shopping results,
sometimes that means in depth information,
sometimes that means gossip,
sometimes that means ......

So, even for the same keyword, the 'best' search results depends on the person and their mindset when they are searching.

Which will steer google towards more and more personalied search results. So context will be defining the search results in the future. By context I mean in this case: earlier searches, location, upcoming special days, personal interests, stuff like that.

Google isn't there yet, but we can rest assured that they are working towards that goal:
Providing the best personalized search results.

So what ranks best?

as always: it depends.

As a best effort answer: I think that trying to give quality content in a consistent manner on your website will work best and will keep working best in attracting traffic. I think this method is performing most steadily and will keep on working most steadily in the forseable future.

Other methods of ranking that basically work by spoofing channels like youtube and google+, etc. are using loopholes in google's algorithms. So they will be the first to be hit by a future update of google. When that happens we don't know, but that it will happen, we can be pretty sure of.

So to be on the safe side: Keep on writing killer content!