Well after researching the poplular Herobrine myths, I took it upon myself to see for... myself...
I made the gold blocks with the moss covered stone in the middle and the netherthing on top, with the redstone torches on each side and lit the netherstone thing.
To my amazement nothing happened, at first... after a while, a cow and a sheep trotted nearby to the statue and they burned themselves alive, a sacrifice?
After that it rained for two whole days, heavily. I was in my newly built watch tower, and that's when I possibly caught a glimpse. I saw what could have been a Zombie standing still but to be honest they didn't look green, and as soon as I saw it I ran towards it full speed, the thing disappeared as I got closer...
Herobrine? I know he's not supposed to be in the game. I know he's not supposed to be real. But... Zombies don't just disappear when you run to them.
The whole thing made me cold and creeped out, felt like I'd really seen a ghost even if it was in a game.
I'm still looking regardless of who says he's real or not.
I'm on Xbox One, and the comment on the title screen makes me wonder - "Blah blah blah studios removed Herobrine from the game, but we're not so sure..."
That's because he was never supposed to have been in the game in the first place. How did they remove something that wasn't in the game, and why are they "not so sure?"
It's an interesting thought, that the creators of the game have placed Herobrine in it and they're still saying he's not when they're not even sure in the first place, in-joke or not, this experience has got me thinking.