Greece may not have a big chance but we are talking about the national team that has the latest MVP of NBA, lets not put that aside, if the teams go head to head or even close for long enough then Giannis may just go berzerk and finish the game for his team, I am not saying it will happen but having a player like that would make any team have a slight chance of going all the way.
USA has a horrible team this year compared to what they used to have but these are still elite NBA players so most likely they will destroy whoever they go against, however it will not be like Angola-USA 60 point game type of situation anymore, it would be more like they are beating them by 10 points on average type of situation. More exhibition matches would have show us more info but the games about to start in 10 days or so, we can still wait.
If you believe that Greece will win because of Giannis, I don't think he will be able to lead his team to win.
He was only an MVP because the play in regular season is different in the Finals, and this FIBA is like the Finals so I believe every team that might possibly face Giannis team have already scouted their best player and like what the Raptors did, if they can stop Giannis, they'll surely win.
You are right man - of course he has the class to find ways, of course Greece needs to take better advantage of him than they did vs Serbia for example - and I am sure they will figure this out - still, the style of play is different than in NBA and if opponents defend him like raptors (and Serbia did), he will have to pass the ball many times, which is not a problem usually - with Greece it is though... we dont have shooters...