While this was announced in yesterday's PTR patch notes, Eyonix posted a bit more information on the new Instance Lock Extension feature coming in patch 3.2.
Check it out below, and feel free to share your thoughts on this new feature!
Quote from: Eyonix (Source)
In the next patch a new feature will be become available that will give
players the option to extend the instance lock, or instance ID of a
raid or heroic dungeon. It will be possible to extend an instance lock
more than once and each extension will grant an additional amount of
time equal to the duration of the original instance lock. In other
words, you'd gain 24-hours if you chose to extend the instance lock of
a heroic dungeon, whereas you'd gain 7-days by extending the lock on
Ulduar. Additionally, extending an instance lock is a choice that's
solely up to each individual, and is not controlled by the group's
party or raid leader. This new option is being added as a means to
allow parties and raids to progress through an instance at their chosen
pace, and should prove to be a useful option available when the patch
is released.
