Samsung is preparing several screen sizes and shapes for the Galaxy S7 lineup, but the launch schedule was never very clear. All at once or like last year where the large S6 edge+ arrived later? A leaked promo image listing the Samsung Galaxy S7, S7 edge and S7 edge+ hints at the "all at once" approach.
The S7+ is not on the list though, that's the flat-screened, XL-sized model. That one may be delayed (launching alongside the Note6 perhaps?) or it could be just an omission in the leaked image.
It seems that regardless of size you'll be getting the same specs – Snapdragon 820 or Exynos, 4GB of RAM, 12MP BRITECELL camera.