Even with the picture that gives a lot of rumors, there is nothing yet confirmed from Samsung. There might be a reason why the device must keep on to the Plus name, rather than having the Edge. We already know that both of the Galaxy S8 and S8 plus will have curved edge screens, but that is not the reason to wear the name as well.
Both of the devices may have the curved edges, but it is also rumored that they will feature a bigger screen as well. In a previous report, we already heard that the devices will feature such specification, having 5.7-inch and 6-inch display respectively. Last year, for the Galaxy S7 Edge, they used a 5.7-inch display, and it was not a disappointment.