Will San Diego win the game SU? The linesmakers have answered that question at close enough to 50/50.
Profiting from futures takes some math. The first question is if you would bet your stake ($140) on San Diego to win the game if this were a SU bet. If the answer is yes, then let it ride. If no, then begin hedging (and continue hedging in the next rounds). Your motivation should not be greed, but making a profit. If you play it right, there is no way you can lose with the odds you got. But this also depends on how much you have riding on other Superbowl futures.
You can also sell your future on an exchange such as Matchbook. This option adds more strategies.
The game itself is a tossup. Key questions are if LT is healthy (I don't think so, because I think he only plays at 100% if he feels zero pain), and if SD defense can blitz Manning successfully (I doubt it, without Merriman). If Manning has time to pick his spots this SD defense will be exposed. Of course the Chargers bring a lot of offensive dynamite themselves.