Going into the final set of matches of the main round let's look at the Olympics qualification implications.
While it is still possible for Brazil to reach the quarterfinals, it would require not only for them to defeat Iceland, but for Sweden to beat Portugal (good chance, even if they rest some players) and Cape Verde to defeat Hungary (less likely) and for Brazil to make up a 24 goal deficit against Portugal. Assuming that doesn't happen then Africa and Europe will be the top two continents and at their respective continental qualifiers two nations will advance to the final qualification tournament while for Asia and Pan America only one nation will advance.
Should Egypt (assuming they don't win the World Championship quota) or one of the European nations in the quarterfinals win their continent qualifier then the 9th place team will advance to the final Olympic qualifier. Should both scenarios happen then the 10th place will also join them. There are no 9th-12th ranking matches. The third place teams from each group will be ranked based on their group performance. Let's look at the chances for each nation to finish 9th or 10th.
Group I
Should the final matches go as expected, will most likely finish 10th. The nation has a great goal differential (+17) and faces Montenegro where they are favoured to win. Assuming they win, they will only have to watch Serbia to hope they don't win by 6 more goals than they did against Montenegro. While a draw for Slovenia won't completely kill their chances they will have to hope for a bunch of results to go their way. Slovenia could finish 9th, but would require Croatia to draw or lose their final match. While is able to finish third in their group it is mathematically impossible for them to finish 9th or 10th.
Group II
This is the most complicated group as four teams have an opportunity to finish third. has the least chance at finishing 10th as they would have to defeat Iceland by 22 goals AND then hope results in the other groups go their way. is in a similar boat in the event they finish third (though actually finishing third would take specific scenarios, they are much more likely to finish second or fourth) due to their horrible goal differential where they would either need to completely demolish Cape Verde or hope for draws in the other groups. has the goal differential (+7) to not have to rely on crazy results, but probably needs to hope Slovenia fails to defeat Montenegro. Netherlands defeating or drawing Serbia would be a huge help too. actually has a good goal differential (+15), but really needs a draw against Sweden so they can have 6 points, but would still require a bunch of results to go their way.
Group III
is the nation on the outside looking in. They technically have control over their destiny and have the added bonus of knowing how many goals they need to win by in order to finish in the top 10. The downside is the Netherlands likely won't go down that easily and Serbia probably needs to win by double digits to surpass Slovenia. Of course, Slovenia could just not win their match and things become a lot easier. not only needs to defeat Serbia, but probably requires Slovenia to not win as they likely won't make up that goal differential. Even if Slovenia chokes they need to hope Portugal doesn't end up in third and if it's Iceland they would have to outscore them against Serbia.
Group IV
could still finish third in the group, but that would require them to loss a 22 goal differential advantage over Croatia. In the event that does happen they are guaranteed to finish 9th. is most likely to finish 9th out of all the teams. They have arguable the easiest opponent among the teams discussed here and any victory guarantees them 9th or better. Even if they end with a draw, they are in a good position to finish in the top 10, but they would have to look at the other results and hope for no blowouts from Serbia or Iceland. In the event pulls off one of the largest upsets in this tournament, their goal differential is horrible where like Hungary they would need to hope for they other third place teams to fail to get 6 points (or have Hungary as one of the third place teams).