No, the heroes are still here; where would they go? I think that at any given time, there will always be someone who stands out from the selfish, self-serving masses... they just don't shout like we sometimes do: "I'm a freaking hero!", banging their head against the wall and slamming their fist on the table. Instead, they quietly and modestly do their humble heroic deeds... sometimes, you forget that such people exist, and you stop believing, but then – bam! – they appear out of nowhere, do something good for someone, and disappear again.
Yeah, they're out there, they're somewhere nearby... :)