Total War: Rome Remastered - Modding
Good News! A), it's here! B), it's moddable!
There will be some quirks and because it looks sooo much better, there will also be more work involved in getting mod assets to match up.
RR still uses .tga.dds files (e.g. dds files but with the .tga name appended so that text files actually just ask for .tga)
Some textures are compressed using the LZ4 system, these also have an additional header section which can be ignored. There will be a version of IWTE along shortly which will de-compress a directory of these textures back to their starting .dds state.
Some textures are DX10 type, these you can probably open but not see the correct information, if you have a recent version of Photoshop you can use this plugin to open them. Otherwise, you need to convert them to .tga using the Texconv tool or similar. The easiest way to use this tool is by writing a .bat file (so you don't have to remember the commands each time!), and example .bat would be:
@echo off texconv.exe -r my_folder\*.dds -ft tga -o my_folder cmd /k