Hello fpbv,
For hardware accelerated 3D viewers the maximum texture size is limited by the graphics hardware. For example, GeForce 580 can render textures up to 8192x8192 pixels size. For older graphics cards the limit may be lower. Generating larger textures than supported by the graphics hardware is useless, as it will be either not displayed, or scaled down to the supported resolution.
Different viewers can have additional limitations on the maximum texture size. For example, Adobe Reader seems to down scale textures to 2Kx2K resolution for display purposes, and completely ignores textures larger then 8Kx8K.
MeshLab seems to downscale textures according to the hardware limitations, so it can display more detailed models then Adobe Reader. It also seems to ignore textures larger then 8Kx8K.
If higher level of detail is required, I would recommend to render a couple of views of the model using PhotoScan orthophoto generation functionality. Using this approach you can obtain virtually unlimited resolution of the final image.