I love this theory that season three will explore more of Benedict's fruity side – cos come on, that Henry Granville storyline was going somewhere!! I don't know that Benedict will be gay per se, but I can't help but feel (hope) his sexuality gets explore more in the season.
Fans also think that season three will introduce to Sophie Beckett, who becomes the object of Benedict's affections in the book. That's prob more likely, TBF.