Currently, there are 6 more remaining squares in the dark barracks, suggesting there are 6 more troops to come and will be filled just like the regular barracks.
http://imgur.com/kAHspqM.jpg
It already takes 7 days and 4m elixir to upgrade it to level 4. Going with the current incremental costs, it will take months to max and be very expensive .. way past maximum of current storage capacity.
So....... really costly and takes so long. How will later upgrades work then??

