While the Twitter post was quickly removed, Videocardz.com managed to grab those pictures, showing the new dual-slot dual-fan design. The picture also shows that it will need a dual 8-pin PCIe power connectors.
The information regarding those two Navi 32-based graphics cards, the Radeon RX 7800 XT and the Radeon RX 7700 XT have already leaked online. The Radeon RX 7800 XT will pack 60 Compute Units and 16GB of 18Gbps GDDR6 memory on a 256-bit memory interface. The Radeon RX 7700 XT is based on the same Navi 32 GPU but with 54 Compute Units, or 3456 Stream Processors and 12GB of 18Gbps GDDR6 memory on a 192-bit memory interface.
As said, the AMD Highlight Show event will be live in a couple of hours, hosted by AMD's own Scott Herkelman, Senior VP and GM at AMD, and Frank Azor, ex. Alienware and now Chief Architect of Gaming Solutions and Gaming Marketing at AMD.