This is from 2000, but despite being a big believer in this principle, I was unaware (until 5 minutes ago) that this already had a name, and in fact was formulated by the godfather of web usability himself:
Jakob's Law of the Internet User Experience
Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know.
This Law is not even a future trend since it has been ruling the Web for several years. It has long been true that websites do more business the more standardized their design is. Think Yahoo and Amazon. Think "shopping cart" and the silly little icon. Think blue text links.
Still as true today.