Will the average fan or gamer be willing to sign up, link an account with coinbase to deposit funds and cash out winnings?  Most people now-a-days are lazy and wont trust an unfamiliar form of currency. That is why it should be a huge priority to advertise to people that hold/are already familiar with btc.  

If GBT were added to polo  i bet we would not only see a huge rise in traffic but also many more bets being placed on the site.

Ultimately a more user friendly D/W  system  would be ideal,  something as easy as say paypal?