With the new ranking system and rank-based units, the eventual economy will switch from a cash one to a valor based economy. Since much stronger units can be purchased for valor than cash, cash will lose some of it's value as a game currency. There is nothing else to buy with it. Why would you build money buildings to get more... cash? The only purpose of cash is to build boost buildings, making the units you buy with valor even stronger. After you maximize your boost, then cash is basically worthless.
Obviously, this is a mid-game concern, not a starter strategy.