The only problem with this is that gold doesn't just affect gold, but can affect any of the others as well. In my own city I had 2 bronze, 6 silver and 6 gold. Under this configuration I was collecting 1 silver token daily. When I placed my 7th gold, Silver now requires 7 pieces. You very well could add bronze or silver buildings and it affect how many gold pieces it takes to make a token.
Someone else posted that EA did answer them on this and that yes the requirements increase the more you have out there, but it will top out. Exactly when and how it tops out is anybody's guess. Feel free to try and figure it out, but you have to account for a lot more than how many gold buildings. You would have to account for how many bronze, how many silver, how many gold, then at what point in your changes did any of the others change. It'll be a daunting task to try and figure out.
