Potentially a bit of a pie in the sky request here but... Tiled Texture Masking is a main stay of modern game rendering techniques that allow the use of lower resolution, smaller data, tillable textures in a manner that visually looks less repetitive, creating a higher quality end result from less intensive texturing.

Second Life could GREATLY benefit from such a feature.

It could be a drop-down option in the pbr materials menu to enable a procedural texture and allow the creator to put in 3 different materials and a map texture that uses the red green and blue channels to define masks for where each of the materials can show up on the face, using whichever channel value is the highest for that pixel with Red>Green>Blue as a priority fall back for any values that are equal. The alpha channel of the map would be ignored.

Each material would still share the same offsets, repeats, animation settings, etc.

To avoid too much strain that would potentially be caused by too many high-res textures. The materials for this feature should be limited to 512x512 at maximum for any texture that is a part of the material. A full suite of 3 materials that use all 4 textures at 512x512 with alpha layers and the map texture including an alpha layer would still take up less memory than a single material that used 1024x1024 textures with alpha channels for each texture in the material at 13mb vs 16mb. Take out the two unneeded alpha channels and remove the emissive mask and the numbers fall to 3.25mb (less than a single 1024x1024 w/ alpha channel) vs 10mb.

Here's a youtube video of the concept by well known blender artist the Blender Guru on the concept. I have set the link to skip straight to the part of his explanation on how the technique works.