Short answer: no.
Long answer: A GPU can not do everything a CPU can do: it's only faster on very specific, highly parallelizable workloads. In the case of emulation, your GPU can actually do very little more than what Dolphin currently uses them for (vertex/pixel transformations).
Doing texture decoding on the GPU is an idea that makes sense: it's parallelizable pretty easily (cut a texture in 16x16 blocks) and the textures need to be uploaded on the GPU anyway. But when the GPU load is already high, doing texture decoding there will actually make everything slower by adding two context switches at every texture load, which might require a complete pipeline flush.
Long answer: A GPU can not do everything a CPU can do: it's only faster on very specific, highly parallelizable workloads. In the case of emulation, your GPU can actually do very little more than what Dolphin currently uses them for (vertex/pixel transformations).
Doing texture decoding on the GPU is an idea that makes sense: it's parallelizable pretty easily (cut a texture in 16x16 blocks) and the textures need to be uploaded on the GPU anyway. But when the GPU load is already high, doing texture decoding there will actually make everything slower by adding two context switches at every texture load, which might require a complete pipeline flush.