The new 15-inch model will be significantly more powerful than its smaller 14-inch sibling, but it will also be dropping specific features including WQHD HDR and the proprietary Side-Dock. A NumPad will be omitted despite the size increase. Expect the ThinkPad X1 Extreme and its ThinkPad P1 workstation equivalent to retail for close to $2000.
https://www.notebookcheck.net/Lenovo-ThinkPad-X1-Extreme-launching-with-rare-GeForce-GTX-1050-Ti-Max-Q-graphics.316548.0.html