I’ll buy it when...

-Edit Background image or video 4K Format
(Loopable, and Custum size or full screen)
-Add a soundtrack, I suggest track involving with the Timeline presentation. It can be the same principle with the Background image or video.
-Custom Size image or Video to give more or less importance to an event
-Timeline background panoramic image following the Timeling progression.
-Inter Timeline on a Event!
-Bring back old features (-Entry by number instead dates)
-Add a kind of google+ friends projects! It can become really popular!

For now it’s not really usefull for me. BUT Please Mr. Adam add those features and it can change the interest of your product! ;)

GouDZ1763 about Timeline 3D, v5.0.2