Well, there should be a Nightwing. And, as I explained in another thread, believably, he'd be in his 30s. Since this is, I guess, the Robin thread, I'll explain in further detail:
So, first of all, I think that both Dick Grayson and Jason Todd should be Robin, Jason after Dick. Now, Snyder's already suggested that Robin was killed around ten years before the events of BvS. BvS takes place in 2015 (while the year is never stated in BvS, we know that it takes place 2 years after MOS, and MOS displayed the year as being 2013. So that makes BvS take place in 2015, which matches up with the year that BvS was supposed to originally release in). That said, Robin is killed by Joker around 2005. I'm establishing that now, and will come back to it soon.
So, Bruce Wayne is 45 in BvS. That makes him 45 in 2015, which means he's born in 1970. His parents die in 1981, making him 11 then. Bruce Wayne probably becomes Batman around age 25, so let's say he starts being Batman in 1995. He's 35 when Robin is killed.
Now, I think that Dick Grayson and Jason Todd should be separate people. I also think that Dick Grayson shouldn't be a teenager when Batman recruits him and takes him in. Sorry, but I just have a problem with the notion of Batman having teenagers fighting hardened criminals on the street. Plus, that way, he's not like Spiderman, juggling school and crimefighting. So, going off of that, I think Dick Grayson should be 20 when he becomes Robin.
So, when do I think Dick Grayson should become Robin? Well, I think he should become Robin in 2000. Here's why:
To have Jason Todd be Robin in 2005, when he's killed by Joker, I think Dick Grayson has to become Robin before that. I think being Robin for 3 - 4 years is enough time for him to have a meaningful history with Batman, while leaving enough time for Jason Todd to have some history with Batman as well. And I think that's important because I think that Dick Grayson has to stop being Robin before Jason Todd becomes Robin. For that to happen, Dick Grayson and Bruce have to have some kind of falling out. And that isn't meaningful unless Dick Grayson spends some years being Robin. So, in that scenario, Dick Grayson becomes Robin in 2000, and is Robin for 3 - 4 years (let's say 3 1/2). And Jason Todd is Robin for 1.5 years. Barbara Gordon can also be recruited and become Batgirl within that time (so, before Dick Grayson stops being Robin and before Jason Todd becomes Robin) so that she and Dick Grayson can have some history.
This would mean that Dick Grayson is 20 in 2000, making him only 10 years younger than Bruce Wayne. Now, I know that Dick Grayson is historically an adopted son for Bruce Wayne, but I don't think Dick Grayson can be 20 - 25 years younger than Bruce Wayne in this universe. Even if Dick Grayson is the Robin that Joker kills, he's killed in 2005. If he's just 15 or even 20 when Joker kills him, he'd still be 25 - 30 by the time of BvS, and in that scenario, what history would he really have with Batman? He'd be Robin for like 1 year before being killed. Not only that, but again, I've got a problem with Batman putting a 15 year old on the street fighting crime. So I don't think that he should be a teenager when he becomes Robin, and I don't think he should be 20 years younger than Batman.
All that said, a Dick Grayson who becomes Robin in 2000 at age 20 would be in his late 30s by the time of the solo Batman film, allowing Jason Todd to be younger (between 20 and 25) when he's killed by Joker. And in such a scenario, if they wanted to do Under the Red Hood for the solo film, Jason Todd would be in his early 30s when the Batman solo releases. This would also allow Batman to have a history and a legacy that includes two Robins and a Batgirl. Not only that, but it also allows Batman to have a dark history after Jason Todd is killed, a history that leads him to the place he is in BvS where he's killing some criminals.
So that, imo, is the most logical way to do Nightwing and Jason Todd. It'd mean you wouldn't have a Teen Titans because he, and Cyborg, wouldn't be teens. And with this history, you have the potential to do several films, like Court of Owls or Under the Red Hood, or anything involving Batman's allies. But you don't have that flexibility if you'd got a Nightwing in his 20s, because that rules out Jason Todd (Dick Grayson needs to be Robin before Jason Todd, and you can't have that if Jason Todd dies in 2005, as that'd make Dick Grayson way too young in 2005, and younger than Jason) and then you have Robin dying at too young of an age.