If this implemented as it is, to me it wont be a fair game anymore and basically we wasted our time and money.
If the point is to make the game more fun, then:
1- You should refund the extra money that anyone paid to make it equal for anyone!
2- You mush have a plan to keep the game interesting for all at the 20+ cities.
Basically, the game is fantastic until you get to the hight range . when you get to 24-25 cities the game is almost over as you already have all the projects ,you are at the optimised level of infra and land, not much is happening at this level and finally the cities are too expensive that requires months of saving. So basically nothing to do other than buying a city once every few months.