It would be horrible, no bones about it. Kane can still go - to a degree - but he's now 47 years old. Sting is 55 (he'll be 56 when WrestleMania 31 rolls around) and was never particularly special in the ring anyway. It's safe to say that a match between these two would almost certainly fail to live up to the hype, especially if it took place on a show the size of 'Mania. Neither man was ever a Shawn Michaels kind of worker, a guy able to carry a lesser opponent to a great match on a consistent basis. If anything, they're both examples of that other type - a wrestler who can be pulled along to a great match if paired with a fantastic opponent. Matches aren't all about workrate, but it certainly helps, and from a purely wrestling standpoint this one would be a stinker.