Anyone who has ever played around with custom ROMs, either developing them, or using them, is likely to know about the CyanogenMod Theme Engine (CMTE). It was one of the first, as well as the biggest theming options for the users of custom ROMs. However, it has been conspicuously absent from the Android Nougat OS for quite a while now. In the absence of the CyanogenMod Theme Engine for Nougat, Lineage OS is likely to replace it with Substratum, as per an XDA report.
Many custom ROMs such as ResurrectionRemix, DirtyUnicorns, etc, as well as many well-known themers like Moelle and Andre Zimmermann too, have moved on to Substratum from the CyanogenMod Theme Engine. It has since been clear that the CMTE was on a decline, but things look more evident now.
While there have been no official reports or confirmations from any of the parties involved, a Slack conversation between a lead developer of Substratum was cited by XDA Developers (shown below). The reply he gets is that Clark Scheff has moved on from the CyanogenMod Theme Engine, basically implying that the CMTE is as good as gone! We are still awaiting an official declaration though.
What is Substratum?
Potentially going to replace the CyanogenMod Theme Engine, Substratum, which is based on Sony’s Overlay Management System, has been rising up the ranks and is becoming quite popular with the users of custom ROMs.
Created by the developers behind the Layers Managers, Substratum is popular because it allows to download, compile, sign, and install overlays like third party apps! After installation it creates and idmap file, which creates the linkage. If enabled, it also notifies the system to refresh its resources and to load new ones. Once the theme package is installed and ready to use, users will be notified! It makes the entire process look so easy.