It is known that the new design is currently being tested to small percentage of people and later will be applied to all profiles.
This is how the single column Facebook new timeline design, below in the picture.
"Facebook is testing a new design with a small percentage of people to make navigating Timeline even easier," a spokesperson for the social network tells NBC News asked about the changes. This sort of test is not unusual as Facebook tests variety of new tweaks to small number of people before rolling out a new change.
Source: thenextweb.com