Firefox 10, which is set to debut any minute now, comes with several new features that will appeal to both regular users and developers. But one in particular should have a huge effect on how Firefox is used and updated, add-ons will be marked as compatible by default, meaning that a new Firefox version won't block your old add-ons until they are updated.
With changes being rather minimal from one Firefox version, most add-ons will work and do not need testing. But it has taken plenty of time for Mozilla and especially add-on developers to adapt to the new schedule.
For regular users, the main thing to remember is that updating to the latest Firefox will rarely mean giving up on your favorite add-ons. What this means is that less people will be reluctant to update to the newer releases.