I really think that Celestia will becoming to the test realm soon or that the build up quests will be coming out soon. Because:
1. There was recently a crowns sale. This means that most likely they will be releasing something soon. I am figuring this because I have seen a pattern of when they have big sales on things such as they did with the 25% of all crown purchases over $25. Most likely I think that they would like too have wizards buy crowns for the new area that is being released, in this case Celestia/Build-Up-Quests.
2. The Build-Up-Quests have been in the test realm between 1 and 3 weeks (I am not really sure how long) and it seems like it has been in the test realm for quite a long time. The Build-Up-Quests isn't a very big thing such as the Advanced Pet System they released recently. Since it has been in so long I expect it might be released soon or possibly part of Celestia (or all of it) will be added on to the Build-Up-Quests.
3. There are not very many characters left in the photo that Kings Isle gave us for Celestia. I have also noticed that they have been releasing the photo updates more and more recently which leads me to believe that they are getting quite close to doing something else with Celestia.
These might not be what exactly happens or even close to what happens they are just what I think will happen due to my observations of what is happening in the Spiral currently.