So with the release of the Maya we have our tall science playstyle with a unique Campus in this pass.
They could have easily gotten a unique Holy Site or even a shrine or library replacement.
It surprises me that those two buildings do not have a unique replacement yet as most of the other tier 1 district buildings do, besides the lighthouse but I don't know what you would do for a unique lighthouse.
So it got me thinking about what other possible Civs could we see in this pass that would give us unique buildings. For me it has come down to 2 to 4 that I think would fit.
Ethiopia: This is probably the best bet to get a unique shrine in the form of either a Monolithic Church or possible even a Stelae. Since the monuments now have unique graphics I think a monument replacement might not be as unique anymore.
Vietnam: They are another interesting option. From my research I've learned that Vietnamese folk religion is dominant in the country and that is unique today compared to most other countries. I think a shrine replacement representing that aspect could give culture and would be interesting. Then again there is the Water Puppet Theater which could be better and is very unique.
Babylon: I know portraying Babylon as a science Civ isn't ideal but that doesn't mean it couldn't at least get a unique library building. If we are going off of city-state types and their suzerain bonuses, it fits. Palenque's bonus was 15% growth in cities with a Campus district which leads itself to the Maya's playstyle right now. So one can assume Babylon has the chance of getting a Tablet House that could hold a Great work of writing slot.
Assyria: They would be another possibility but I'd rather them have a Royal Library Govt. Plaza building and some sort of Encampment (building) replacement.
Edit: Now that I think about it they have finally revealed the Observatory as a unique infrastructure that was a missing universal building from Civ 5. Does that mean they are holding back on others as they will be unique like an Opera House for Italy?