In the newest build of 2.8 as of today (June 8th 2019). I am trying to sculpt an object while also having a specific texture show on the same object. I cannot find any way to do that. As soon as I switch to sculpt mode I get some sort of matcap material and I cannot get a texture to show up in any renderer under any settings I tried. Is there I solution?
EDIT if you want to take a stab at solving this please make sure you have an object with Multires modifier applied to it.
EDIT 2 Looks like it's a bug that's been reported already https://developer.blender.org/T63581