Serbia is a solid team with many experienced players and I think it is the time to win this tournament.
It's their best chance now because although the team USA is the favorites to win, I don't see them as a super team unlike the Roster they have in the past.
I like betting on the underdog but this dog has a chance of pulling out a win, and when it comes to experience, I agree with you that they have the edge as most of the players of the USA team are young players.
Indeed, this is the best time to bet for Serbia to win the World Cup this year and their odds is good. I have seen the friendly match between the US and Australia and they were not so dominant on that win though they will make some adjustment but they are beatable. Serbia has a lot of outside shooters which could make the difference if they face US in the Finals.