SPOILER ALERT: This contains major spoiler from the Comic Con Batman v Superman trailer.
Ok so THIS is just a fan theory, nothing official.
Following the release of the Comic-con trailer of Batman v Superman, many fans have been coming up with their own theories but none of us have been fully able to crack down the trailer because of its elements, and unknown roles and motives of the characters. Well I too tried to solve the mystery of the trailer and came up with this Theory :
Bruce states in this scene :
"20 years in Gotham. How many good guys are left? How many stayed that way?"
So "How many stayed that way?" could mean that Jason Todd, the Second Robin who was presumably killed at the hands of the Joker, has already returned as the Red Hood before the events of "Batman v Superman: Dawn Of Justice" meaning that the good guys didn't stay good.
My theory doesn't just end here fellas, there's one more thing to discuss. Bruce said "How many good guys stayed that way". "How many good guys" is not just One guy, it's plural. Interesting? Y'see, in the sequel to Frank Miller's The Dark Knight Returns, "The Dark Knight Strikes Again", Dick Grayson, the first Robin is fired long ago by Batman because of his "cowardice and incompetence" who then returns as the main villain of the novel. So I mean to say that Jason Todd as the Red Hood and this villain version of Dick Grayson have already appeared in the Universe of "Batman v Superman: Dawn Of Justice" which is why Bruce said "How many stayed that way?" meaning the good guys turned BAD!!