First off: there are no new content updates planned. Why make this post at all, then? First, I updated the mod late last year, to run on the current Rebellion patch; due to how ModDB works this didn't count as an "update" and I want to let people that they can play this without reverting to a version from 2014. But also, I want to describe just why work on this mod stopped.
The main reason has to do with performance issues. There were two core elements that this mod developed around; first, big battles with tactical elements, where you took damage from being flanked. Second, logistics, where supply mattered. The second part ended up killing off the first, and finally the mod. Sins was never developed as this kind of game, and asking it to simulate it on this scale led to memory leaks that completely stopped new development as the mod went through a series of reworks to try to improve performance. Some of this was due to the original Sins engine, which had issues with this even unmodded, and the move to Rebellion alleviated some of this, but also created new problems.
Take research. In the first version, this mod had a tech tree for each faction, where you could research new admirals and new flagships. Each one spawned once, using what was essentially a bug. When Rebellion was released, this bug was patched, and that also broke our research system, which is why the tech tree for this mod is empty.
There were other issues as well; the debugger for the game doesn't have an option to log to file, but stops the game every time to pop up an error message which may or may not make sense to someone who didn't program the game. The version of the model exporter I worked with didn't export textures correctly, which meant that models like Iserlohn had gigantic ugly seams on them (if you look closely at the Artemis models you can see this). Ironclad kept reworking the game file format every other patch in small ways that completely broke the mod.
Basically, this mod was making Sins do things it was never intended to, and trying to do it was exhausting.