Holo matches perfectly with the black iPhone 5's design
Just a thought:
Holo is a stark, dark, minimalist UI. It's got sharp corners, dark colors, and no fake gloss/skeumorphism. It's minimalist in meaning of the word.
The black iPhone 5, hardware wise, is stark, dark, and minimalist. The surfaces are clean and solid, and other than the rounded corners, looks quite sharp. Basically in complete contradiction to iOS, which is bright, rounded, and heavily glossed and skeumorphed.
Just imagine Jelly Bean on the black iPhone 5. The two were made for each other.