No not all factions would get a massive reform. Most will have units which progress over time, as there was a general increase and evolutions in armour. Which will be represented by using the armour upgrade function. This however will not be dependant on the creation of a building but rather meeting certain conditions set by the script. Some factions will indeed see much larger and fundamental changes, that are more than just some changes and improvements in armour. The Romans are a great and good example of such a faction. They are of course not the only ones, but for details and other reforms I'll have to refer you to future previews.

btw: welcome to the .org!