I just had a look at the roadmap of this engine. It reads very impressive:
http://www.terathon.com/wiki/index.php?title=Official_Roadmap

He plans to integrate new terrain / foliage renderer and the ability to load zones in the background. This smells like big Oblivion-like-terrains or really big indoor levels.

Some other interesting features will make it directly into the engine so you can use them easily without the need to script them yourself.
And the blend maps could be used for facial animations.

Fireball is the codename of the next version of this engine.

By the way: He delivers new updates every week, not only bug-fixes, mainly new features. Eric must be a machine of a coder

• New terrain system [Fireball].
  
• Foliage system [Fireball].
  
• New soft shadow solution [Fireball].
  
• Dynamic shadow mapping [Fireball].
  
• High-dynamic range (HDR) rendering [Fireball].
  
• Full physics system [Fireball].
  
• Background zone loading [Fireball].
  
• Script conditional logic.
  
• Skinnable GUI elements.
  
• Transparent warping effects (heat haze, etc.) [Fireball].
  
• Direct support for XInput controls.
  
• Bump-mapped surface markings [Fireball].
  
• Engine-level mover support (elevators, etc.) [Fireball].
  
• Morph targets (blend shapes).
  
• Material import moved to core.