The board theme has been changed for a few reasons:
1 - It was too busy
2 - There wasn't enough contrast, and it was difficult to tell which boards were unread
There are multiple colours available (blue, green, yellow, purple, red), and I'm in the process of looking for another one.
In short... no, it isn't being changed back.

Although, I believe you can select any theme you like from your profile.
Click:
- Profile (or User Control Panel)
- Board Preferences (It's on the left)
- My Board Style
There are a few there, so anyone can pick what they like!