The GTX1180 shows up on Techpowerup.com as a 12nm GPU based on an unannounced GV104 graphics processor. The GTX1180 is stated to handle 4K games with ease.
While we should not take the details as final, the idea that the GTX1180 was already given a placeholder and a title, more or less confirms that the successor to the GTX1080 is coming very soon.
The card comes with a whopping 3584 shader units and 16GB Gddr6 memory.
Check out the other details here: