According to a post on TSO-E Blog, all production cities would go offline on the 21st of February, permanently.
This means that the merges would start a few weeks after that and we can never enter those production cities again. Meanwhile, all users are able to play in Test Center 3 and EA-Land.
“ The update will provide eight (8) available slots for EA-Land. Characters from ALL cities (except Test Center 3) will be filling those slots. (Important Note: if you have more total characters than eight (8) in those cities some of characters will no longer be available so make room for all your characters).”
– Quote from the TSO-E Blog by Greg