I have bookmarked this thread, and I will keep my eyes open.
This year new TVs have come out with Ultra-HD, 3840x2160 pixel. This means, my Winamp-Milkdrop-Videos in 1920x1080 pixel on YouTube are already "Old Snow From Yesterday" (a German phrase). Otherwise bigger images could be allowed, 4096x4096 pixel and 8192x8192 pixel. I don't know, if the pixel sizes are related to the Milkdrop Version or not.
I would be interested, if in Milkdrop 3 also GIF will be supported as image-file-format, with and without GIF-Animations. In Milkdrop 2 as supported file-formats for textures JPG, PNG, DDS, TGA are listed. For BMP and DIB I have read something with "puke", and BMP is heavy to load also in Windows Explorer.
For me it would be very important, that presets can be renamed, re-rated, edited and saved without problems. Windows Vista and Windows 7 have shown me my limits for Milkdrop 2, and I have no Windows XP anymore. For Windows 8 / 8.1 and Windows 10 I suppose the same. Maybe in Milkdrop 3 these problems will disappear.
Hopefully Milkdrop 3 can handle also with very much presets & textures. I am thinking about the maximum limits of 100000 presets & 10000 textures, although I think, maybe 3000 textures will be enough for me.
Before leaving the school, I have written a Five in Maths, which was very bad, so that I myself would be very bad as a software developer. I myself never would be a good plugin author, skin author or preset author.
But I believe, that there are some professional forums members incl. very good developers of Milkdrop 3, and maybe Milkdrop 3 will come out some day. For now, I am very satisfied with Milkdrop 2.25c, and I have customized the Milkdrop folder in my Winamp, especially with very much new random textures. Currently I have over 2100 textures there.
I wish You all good luck and a good future for Winamp 6 and Milkdrop 3...