Will Favre retire?

Can Protrade, a stock market for athletes, be used to estimate the chance that an athlete will retire? The Protrade market has players "earn" dividends based on their on-field performance and theory indicates that, like a stock, their value would be equal to their discounted expected future dividends. A player's value goes to zero when they retire. If we look at the example of Brett Favre his price is around $87 and he has earned about $25 in dividends so far this season. He is clearly not going to come anywhere close to $87 for the remainder of this season, perhaps an indication that he won't retire, but sign with a new team. There are a couple of potential issues with this analysis. First, you can't short a player in Protrade, you can only buy and sell. Second, this assumes that the money supply is controlled, which Protrade says it does. Nonetheless, it looks like the market is signaling another season for Favre, after all he couldn't be worse than whovever is playing QB for Chicago this week, could he?