The following article contains spoilers from Future State: Gotham #17, on sale now.
In the future, Nightwing has gained access to a level of psychic power that makes him more superhuman. It's had the benefit of letting him predict which moves people will make in combat, while also causing him to become harsher to those around him. However, Future State: Gotham #17 (by Dennis Culver, Geoffo, Giannis Milonogiannis, and Troy Peteri) proved that Nightwing's new power, while formidable, is not infallible.
He's overlooked small details within the grand scheme of things. These include an unknown tracker and a distraction in a fight. These things, while insignificant, might play a greater role in the future. Nightwing has predicted some catastrophe that is coming to Gotham, and he's hellbent on making sure he's the only Batman when it arrives, but these slipups on his part hint that he may not have the whole picture. If so, then Nightwing might be wrong about everything.
The first instance of the holes in his powers came from Oracle, who put a tracker on Nightwing during his fight with the rest of the Bat-Family. He seemed in complete control of that conflict, yet all his powers of perception failed to notice Oracle perform one of the oldest tricks in the book on him. Later, Hush managed to get the drop on Nightwing by distracting him during their fight, allowing Batman 666 to strike him from behind. Hush even taunted Nightwing that his powers don't show him everything.
So, while the last few issues have built up Nightwing's power, this one is dedicated to sowing the seeds of doubt in readers. From an outside perspective, readers know Nightwing has foreseen something horrible and is preparing for it. From that angle, it appears as though he's the only one who knows what he is doing. However, this issue points out that Nightwing can only really interpret the big picture, but fails to notice the smaller details that comprise it. A missed bit of information here or there can change how someone interprets something, and Nightwing is only human.
If this tracks, then there's a chance that there are little parts of his visions that he overlooked or simply didn't consider important enough to factor into his plans. Even the smallest change could have ramifications for the future. For example, consider what might have happened had Bruce Wayne and his parents not taken a turn into Crime Alley, or what could have happened had Haly's Circus not stopped in Gotham. A slight change in plans could throw off the future entirely.
So, why are his powers failing him now? One possibility is that they were always like this. There is still so much not known about dosing on as much brane as Nightwing has, and the consequences of it. Alternatively, he might be running low on brane, as he used a lot of it to keep up in this latest conflict. Or perhaps his mind can't keep up. There is a lot of information to sort through in when predicting the future and a human mind isn't built to handle that kind of information overload. Nightwing may very well be scrambling to understand what it is he's seeing. Either way, it's clear that his future sight is not perfect, and that could have consequences for the calamity he predicted.