Because then you will get a server that is broken from X level to Y and fixed from Y and above. Thats not the proper way to do things. You don't clean your house by putting all the dust and shit in one room.
So will there be a big shake up patch(or series of patches rather) on this server or did you give up on that idea and you're just working on the new server?
You said you won't stop updating this server but at the same time you also say it's pointless to add new content either.
You also stated that you might leave at the end of the year again.
What is a very rough plan for the next, lets say, 6 months?