Samsung is planning to launch another Windows Phone device after the ATIV S. The project has been codenamed Huron and the model number cited is SM-W750V. The phone is being made exclusively for launch on Verizon, which can be seen in the naming convention Samsung uses where the 'V' at the end of SM-W750V stands for Verizon.
Leakster @evLeaks also says that the phone looks a lot like the older Galaxy S, which is quite evident from the image above. Furthermore, the phone also appeared on GFXBench benchmarks, where it revealed that it has a 720p display, but that's not necessarily correct as the site also lists the Lumia 1520 to have a 720p display. There's also mention of a quad-core Snapdragon processor with Adreno 305 GPU, if these specs materialize then we will be looking at a mid-range smartphone rather than a Samsung flagship running Windows Phone 8.1. WP 8.1 is slated for an April release at Microsoft's Build Conference which starts April 2nd. We will have a lot more to see then including several flagship devices from various other OEM's including Samsung.