It kinda is supported already.
Both the message and email view support texture loading, buuuuttttttt, you will have to load the image texture somehow, maybe with CreateRuntimeTextureFromDuiHandle - Natives @ Cfx.re Docs, then add that image into the text with html, like this: <img src='img://textureDirectory/textureName' height='128' width='244'/>
This post shows how scaleforms support html: Using HTML, images and blips in scaleform/texts
With the DUI, and some external Snapmatic image host, you can technically send images to other users, but you will need to create a messaging back-end that supports that. It should work, but I have not clue how to load external images.