The upcoming patch on Friday (2018-09-21) will reduce the max number of cities from 8 to 4.

There is a very good reason for this, but I don't want to spoil the future surprise, rest assured it's not a reduction ''Just because'', and it will make sense in a future patch.

As a result of this, all cities and buildings will be wiped on Friday, but planet stockpiles will NOT be wiped.