If you put together Sasuke and Itachi's Mangekyou Sharingan, you might get a general idea of what it will look like when Kishimoto decides to reveal it to the manga readers.
Itachi's Mangekyou Sharingan
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Sasuke's Mangekyou Sharingan
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Sasuke's Eternal Mangekyou Sharingan, possibly something like what is seen below
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What's equally interesting is, the powers Sasuke will gain with his new eyes, and how they help him to fight Naruto when that fight comes around.