I am creating a sprite engine that uses the concept of "graphics banks" to speed up rendering using batches. I was wondering if anyone knows if 1024x1024 textures are widely supported enough these days to "count on", and/or if there is a way to find out how far back there has been support for 1024x0124 in terms of graphics chipsets / cards, like a chart or something, and from that decide based on estimated compatibility % if I should go with 1024x1024 or limit banks to 512x512 (which I have a feeling is more widely supported, if you count integrated accelerators)
According to this SO answer "what is the max size of the texture iphone can support?" the iPhone 3g can support 1024x1024 texture sizes. That phone was released in 2008, which leads me to believe that most desktop would be able to support the same 5 years ago.
The GL_MAX_TEXTURE_SIZE is defined by the implementation. Wild Fire Games has also been kind enough to offer their OpenGL capabilities report which has max texture sizes from their data set. As of writing this, only 18 out of 33085 (0.05%) users have reported to not have the ability to render a GL_MAX_TEXTURE_SIZE 1024 or more.