The August dates at Bromont have been given to Belgium, leaving no North American opportunities to gain Paris qualification points.
In this final leg of the series, an all-female British team led the way, ahead of New Zealand, France and Germany.
This victory marked the second time in a row Belgium has claimed the prestigious Nations Cup prize in Arville, edging Germany and Italy.
Strong performances by Colleen Loach saw her 2nd and 3rd in the CCI4*-S; Team Australia had only one rider complete.
A selection event, and the only North American Nations Cup stop for eventing, takes place August 19-20 in Quebec
A keen young team won one of the most hotly-contested legs of the series among 12 squads, while some used the event as a tune-up for Pratoni.
The squad have won team and individual prizes in both their appearances in this series so far and are coached by Olympian Andrew Nicholson.
Strong cross-country and show jumping performances put the team well ahead of the Netherlands and third-placed Austria.
Tom McEwan led the GB squad from start to finish in the 4*; in individual results, Canadian Karl Slezak places 21st with 'Chocy'.
A full season of team eventing kicks off at Pratoni del Vivaro, Italy, this weekend as part of a test event for the World Championships.