Path of Exile Grinding Gear Games talked about the following expansion.

In a recent post on the Path of Exile team forum, Grinding Gear Games talked about the next expansion, as well as how the development differs from previous extensions and updates. This post described the difficulties that the team faced, as well as the difficulties that still continue to hinder them, which is why they intend to release their extension only in December.

This post is a lengthy outline of some of the initial concerns the team had in the game’s early development cycle, which has since moved on a path that was unsustainable for the foreseeable future, in a post-pandemic world. The vulnerability of their development cycle has revealed the teams ‘ weaknesses, which include overall development volume, feature creep, and General unexpected events that they may have never seen before, which has now led the team to redesign their development process to be more resilient and potentially fruitful.

”At the end of the Heist development cycle, we had a serious internal discussion about how we could restructure our development process so that future extensions are less risky. The result of this discussion was an experiment that we decided to conduct over the next three-month cycle.
We have defined a very specific framework for the December 3.13 expansion. it contains everything you need to expand the great path of exile, but nothing more.”

At the moment, their overall goal is to reduce development time by delivering exactly what they are aiming for.

“If you’re interested, this is an expansion of the Atlas (like war or conquerors) with a battle League in the area and a few other pieces. We will also announce it a little differently than usual. Stay tuned!”

Heist was released recently, namely last month and has since gone through some improvements and changes.