Even though the character of John Constantine has only been around since 1985, he's really showing his age these days...and that's a big problem. The star of DC Comics' VERTIGO series Hellblazer is a rare comics character allowed to age in real time, which means he was officially 35 years old in 1988 and 40 in 1993, making him now 58 (or very close to it) in 2011.
So as far as I'm concerned, it's way past time for a reboot. Something has to be done before Constantine ends up in a wheelchair or even worse, one of those scooters, sucking on an oxygen mask. It doesn't have to be a complete continuity reboot, mind you, maybe something that takes him back to just after Ennis' original run and then freezes his age like most comic book characters.
According to Bleeding Cool, Constantine is scheduled to return to the DC Universe after the upcoming even series Flashpoint. His reappearance in the DCU is probably related in some way to Swamp Thing's return in the pages of Brightest Day, although there has been no indication that Hellblazer will cease publication. It could simply be there will be a younger, sanitized DCU version of the character while the older, less restrained version continues decaying year after year in his VERTIGO series.
Hopefully, the VERTIGO Constantine is allowed to continue, but not in this current aged state. I miss seeing him in his prime, without a scar on his face and having both thumbs and color in his wild hair. I could always go back and reread earlier stories, of course, but if Superman and Batman get to have new adventures without the sign of wrinkles or even a hint of gray, then why shouldn't Constantine? If he can beat terminal lung cancer, then surely he can beat old age.