Yes I agree that's great idea. Devs must make new technologies to tech tree and this is that what should be implement first. These technologies don't need higher thoughts it is simple, now when we have specified upper limits of available level of buildings - that could be ingore with "new age" and replace them on more size of squad,
Why? - It is PvE where we must discover 'all' provinces, the power of further provinces is greater to them is further but our power is fixed at the time of completion of the tech tree - no more options for upgrade units or some bonuses for them.
Now the age could be specified for PvE options like bigger squads, some bonuses - any, that's creativity of IG to make the age like possibility of continue THIS PvE system with more and stronger provinces.
Before They introduced us to complete full options to improve ourselves cities on completly upgrade buildings for normal thinks in game, and now continue the story on battles system in provinces. Next step is that we can produce more goods WHICH we now have finished in buildings, now we need more of Provinces to improve bonuses of these GOODS - now back to the starting point.