The accepted practice, in agreement with the majority of poskim, is that grape juice is treated like wine regarding all halachot, including, as you assume, Kiddush.[1] This ruling applies to exempting other drinks from berachot, both beracha rishona and beracha acharona.[2]
However, the status of grape juice, or wine for that matter, should not be taken for granted regarding exempting other berachot. First, some wine and grape juice is diluted to the point that they lose the status of wine regarding Kiddush and berachot.[3] Since it is difficult for the consumer to know when it is too diluted, it is preferable[4] that the hashgacha on the wine or grape juice state that it is valid for Kiddush and that its beracha is HaGefen. (Some hashgachot add that it is valid even for Sephardim, who are somewhat stricter on this issue).
The second point is that one needs to drink a certain amount of wine to be exempt from a beracha on other drinks. The Bi’ur Halacha[5] rules that in order for other beverages to be overshadowed by the drinking of the wine, one must drink a minimum of a m’lo lugmav of wine (roughly, a cheek full that looks like two cheeks full, or approximately 2 fl. oz.). If, at Kiddush, one person had the requisite amount and others had just a taste of wine, then it is highly questionable whether the others are exempt from making a beracha on a subsequent drink.[6] It is also important either that the drinks are present at the time of the original beracha or that the person had them in mind.[7] A guest at a kiddush normally has in mind to eat or drink from whatever the hosts/organizers will serve.[8]
The beracha acharona of Al HaGefen, recited over grape juice and wine, also covers the beracha acharona of other drinks.[9]
If a case of doubt arises, it is best to make a Shehakol on a solid food before partaking of the other drinks, so that this beracha will be clearly warranted and cover the drinks. Alternatively, one may have someone who did not drink wine make a Shehakol on his behalf.[10]