Sam Mobile “can confirm” that the upcoming flagship will be called Galaxy S6 - but that’s hardly a surprise. The website also notes that we should expect to see a Galaxy S6 Edge variant, which would, indeed, offer a curved display, though it’s not clear if it’s going to be curved on one, or two sides.
Assuming that all this is true, it looks like we’re going to have a regular Galaxy S6, with a flat display, and a version of it with a curved screen. The latter may be released only in select markets - just like the Galaxy Note Edge.
As a reminder, the rumored specs of the Galaxy S6 include a 1440 x 2560 (Quad HD) display, a 5MP front-facing camera, 16 MP or 20 MP rear camera, and a Qualcomm Snapdragon 810 or Samsung Exynos 7420 processor. The smartphone should be made out of metal - at least partially.