well,got to deep into the stuff of bandwidth
as for the textures, well, i got no proves, but is interesting to note that there is another feature of the specs of the sdk of an alpha kit f wii u that has been claimed to be supported
first was multi threading rendering in project cars, then 1080p in a single pass, now its the texture sizes
http://www.nintengen.com/2012/07/wii-u-confirmed-specs-from-sdk-gpu-info.html
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Graphics and Video
Modern unified shader architecture.
32MB high-bandwidth eDRAM, supports 720p 4x MSAA or 1080p rendering in a single pass.
HDMI and component video outputs.
Features
Unified shader architecture executes vertex, geometry, and pixel shaders
Multi-sample anti-aliasing (2, 4, or 8 samples per pixel)
Read from multi-sample surfaces in the shader
128-bit floating point HDR texture filtering
High resolution texture support (up to 8192 x 8192)
Indexed cube map arrays
8 render targets
Independent blend modes per render target
Pixel coverage sample masking
Hierarchical Z/stencil buffer
Early Z test and Fast Z Clear
Lossless Z & stencil compression
2x/4x/8x/16x high quality adaptive anisotropic filtering modes
sRGB filtering (gamma/degamma)
Tessellation unit
Stream out support
Compute shader support
"
