As it stands right now, if you have not placed the maximum ql controller that you can at your base, there is no way to place a higher ql controller there without losing your base.
There are 2 issues here:
1. When you destroy your own controller, the entire base goes up in flames.
2. There is a period of 3 hours where your guild cannot place a controller in that area.
The issue that my guild is having is that after many many shopping trips, we came across a ql223 controller. We currently have a base that can support that, but it has a ql200 controller there now. We placed this early on when we did not know that odd ql's came up in the shop.
Now, after spending many millions of credits getting it up and running, there is no way for us to place the higher controller w/o losing it all.
Although shadowlands is a bit far away at this point, I do forsee ql300 controllers being obtainable at some point. Will those that currently have 200-300 land and defend it until shadowlands be forced to completely remake their base in order to place a 300?
I do know there there is an option of having a guild that you trust place a controller there after you destroy the base and then later take it down so you can rebuild, but I find it horrifying that there is no system for doing this.
I realize that this sort of thing would take some work in the coding, but I would be happy if a GM even were able to keep the base up while the tower was replaced.