Not sure what the plan might be for the colony overview / management screen (that lists all owned colonies), when it makes it in -- something similar to GalCiv2, I would guess.
However, with the change in GC3 allowing per-colony economic/research/manufacturing adjustment, and anticipating maps with lots of colonies to manage, I don't think the old style management screen will be enough.
In GC2, eventually, you could see and select a specific colony's focus on this screen (be it a focus on research/social/or military), but in GC3 you have the whole economic color wheel plus the social/military slider, allowing much finer control over each colony. Needless to say, with 30+ colonies, this has the potential to be overwhelming.
I have two starter ideas:
1) use Governors. You would create a Governor and name them (eg: Gov.Jenny), then set their economic wheel ratios (eg: 50% wealth, 25% manufacturing, 25% research, and manuf. slider to 25% social).
Now, from the colony management list, you could see the current Governor, and set it too.
2) Using standard Windows multi-select controls (ie: using CTRL and SHIFT-clicking) to highlight multiple colonies in the list, you could then click a "Govern" button to bring up the economic wheel. Whatever settings you choose would apply to all the selected colonies.