I'm sure you've all seen some riff on "Why was Lois Lane never able to figure Superman and Clark Kent were the same person? He's just wearing glasses!" But if a comic is purporting to reflect today's society, then the notion of keeping a secret identity is ludicrous.
We are captured on film every day. Security cameras, camcorders, cell phones, increasing news outlets... Cameras are so ubiquitous to our culture as to be invisible, even when they're in plain view. Which means that a person, even in some kind of mask, is going to be seen by someone even in the middle of the night. Furthermore, a hero in today's society is going to become an instant celebrity, meaning that people will be going out of their way to record their actions.
Now, there's going to be someone out there who take so great an interest in the superhero that they're going to start tracking their movements. Easy enough to do with readily available tools like GoogleMaps. Inevitably, the hero's going to develop a pattern of some sort and it wouldn't be at all difficult to triangulate on a central area of interest. A base of operations, if you will.
Then it would only be a matter of doing some pattern recognition between images of the hero and images of residents of that area. And while that might not garner a 100% guaranteed identity, it will narrow the field of candidates considerably, allowing someone to focus on a handful of individuals for closer scrutiny.
I don't think it would take long at all for a Batman or a Booster Gold to be uncovered. It might take a little longer for a shapershifter (Martian Manhunter) or someone whose costume hides their features (Iron Man) but I think that, in today's world, somebody would make it a point to track these guys down. Heck, Peter David did almost that exact story over 20 years ago in Peter Parker, the Spectacular Spider-Man #103, and two decades of technological improvements have made things infinitely easier to sort through and analyze data.Heh. Yet another instance of Jack Kirby being ahead of his time, ditching the notion of secret identities back in the 1960s!