So now that we are to the round of 16, I think my reply to Sanjay Reddy's question can be evaluated. Note that from the 16, 5 are from Latin America (Argentina, Brazil, Colombia, Mexico, and Uruguay), one from Asia (Japan) and 10 from Europe (Belgium, Croatia, Denmark, England, France, Portugal, Russia, Spain, Sweden, and Switzerland). Of those 6 have already won a World Cup (Argentina, Brazil, England, France, Spain and Uruguay) and 1 played at least a final (Sweden, lost against Brazil in 1958). Note that no countries from the Middle East or Africa passed the initial phase.
There is a good chance that the winner will be a previous champion. I wouldn't discount the possibility of a new champion, but in that case the likelihood is that it would be another European team (my bets would be on Portugal if CR7 plays incredibly for te rest of the tournament, or Russia being at home). Probably less likely, a Latin American one could also win (if Mexico plays like it did with Germany). But the best bet would be a previous champion.
Path dependency is really strong, and that suggests that games have been close not because the skills are more or less the same, but because it's relatively easy to play a defensive game and make it very hard for the good teams to move forward.