Well, they already have the FIBA World Championships and the Olympics every few years so I don't really see the need for an NBA v. Euroleague All Star Game. Also, wouldn't this be a scheduling and logistics nightmare?
Maybe a US vs. the World format like the NHL used to have where you take the best U.S. players in the NBA and match them up against the best foreign players in the NBA or something would be a more reasonable format.
Although, the all star game is already intended as an exhibition game anyways so I really don't care what the format is.