The XPS is and will remain a good value, but those who only look at the superficial specs will be more impressed than those who look at the details. The XPS already offered 32 GB RAM and a 4K touchscreen, so the main new parts are the processors. The Kaby Lake isn't a great leap from the Skylake in most respects, should save some power. Even with the larger battery, though, don't expect great battery life with DDR4 RAM, especially if you get 32 GB. The GPU looks like a solid jump. The MBP's ports will remain more powerful, with better external monitor support.
I think Macs will survive.