Sharing my current concept for new Buildings to be added:
(Still thinking about it, but I am 90% convinced that this is the solution I want to head for.)
The absolute necesssaries ones with Professions (- there are no good alternatives)
1) Cooking Oil Trader's House --> absolutely necessary (there is no alternative for
Olive Oil and
Canola Oil)
2) Confectioner's House --> absolutely necessary (there is no alternative for
Chocoloate, will also have
Vanilla)
The high priority ones with Professions (- alternatives possible, but this will look anf feel better)
3) Leather Taylor's House --> high priority (or other Buildings get cramped, for
Padded Leather Coats and
Goat Hide Boots)
4) Cloth Taylor's House --> high priority (or other Buildings get cramped, for
Commoner's Clothes and
Nobleman's Clothes) *
* Those are Yields that will be added by replacing 2 other Yields I am currently not really happy with.
I will replace boring "Household Goods" and boring "Field Worker Tools" because we arleady have "Luxury Goods" serving the same purpose.
(Currently those are just consumables to be bought in Europe, which only few players will most likely use.)
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2 Building Slots to be reserved for the future (- will for the moment get an existing Building without any Profession Slots)
e.g. (Just possible examples)
5)
Courthouse (not yet existing) --> this building chain is needed for
"Crime and Law" feature
6)
Inventor's House (not yet existing) --> this building chain is needed for
"Social Progress" feature
7) Something else that sounds even better ... 2 reserves slots should be enough though.
--> Slot 1
will be reserved for now by putting
Market on it (giving other buildings more space)
--> Slot 2
will be reserved by putting
Tavern on it (giving other buildings more space)
Comment:
For both
Market and
Tavern there are also still concepts to give them Profession slots.
(That is basically the reason I want to use them as "placeholders" to reserve the slots.)
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To do so I will need to add
1 single new row of buildings in the Building Screen.
(1 single new row of buildings ==
6 buildings with Professions slots.)
1. Slightly shifting worker slots more above the Buildings.
2. Repositioning Buildings to slightly reducing distance of rows.
But all of that should be possible without impacting usability.

(Most likely I will not even need to reduce size of 2D images of Buildings.)
I use a player screenshot from Release 3.1 to visualize the idea.
(There is still enough space in City Screen for 1 more row of Buildings.)
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Long story, short summary:
I will add
4 new Building Chains for now and reserve 2 slots for the future.
To do so I will give the City Screen 1 more row of buildings.
- Cooking Oil Trader's House
- Confectioner's House
- Leather Taylor's House
- Cloth Taylor's House