According to Dell, Kaby Lake-G caters better to casual mainstream gamers while the Alienware brand will stick to hardcore gamers and enthusiasts with the familiar Intel H-series and Nvidia GTX GPUs. The Intel-AMD processors will instead be used for Dell's mainstream families like the XPS line to provide GTX 1050-level graphics.
https://www.notebookcheck.net/Alienware-has-no-current-plans-for-Kaby-Lake-G.301014.0.html