As far as the nature of the match it will just be one rapidish game with a coinflip deciding the colors. The bet isn't who will be the best player after one year, it's just who will win that game. It's gambling, we're gamblers. Plus that way the loser can still claim they would have won if the format were a week long Kasparov vs Karpov struggle.
Ok, one game.
What happends if it ends in a draw?
Lets assume Cunningham is at 1400 today and Lederer 1900.
Its a hell of a climb in one year for sure.
Mr Garry Kasparov started out at chess at age 6, went to a chess club at age 7 and reached Russias class 1 at age 9 (About 2000 rated.)
The year after that he reached Master class, about 2150
Today, once in a while the chessworld discovers a 12year old Grandmaster who has just been playing for a few years, and its certainly a lot easier to reach 1900 than 2500
But the big problem is that these kind of climbs are almost unheard of from chessplayers already at an adult age.