Guys, Mike Rossi is never going to break 20 minutes for a 5K. I guarantee you that.
I think he will probably cheat at a 5K somehow and so have no actual evidence that he ran the time in question. Additionally, the circumstances will probably point to the fact that he didn't really run the full 5K but it won't be up to the Barb McCleever standard so he always insist that he did.
He won't actually demand the $10,000 from Letsrun, but when Rojo rightfully doesn't pay him he will act like they welched on the offer thus simultaneously suggesting that he did run sub 20 ("proving" he also must have run the 3:11), and that Rojo is a "troll" that doesn't make good on his bets so everything written against him on the internet must be untrue.
Anyone that knows anything about running will continue to know that Rossi cheated. Anyone that knows Rossi will continue to know that he is a huge loser, assume he did cheat and snicker to each other behind his back. No one else will care.
Basically, it will be the same situation that we are in right now.