That’s the latest rumor at least. Emphasis on rumor.
Cumberbatch is known to be a fan of the Star Wars movies and does of course have a history with J. J. Abrams. So it’s not that far fetched. But as far as I can tell no one is actually pointing to a solid source for the rumor yet.
It’s a far more encouraging casting rumor to me than anything we’ve heard up to now.