It would also be possible to have two different kits based around the same camera for different purposes. If I end up with the Z7, which I have on preorder and am seriously considering, the concept would be:
Long hike kit (up to hundreds of miles):
Z7
24-70 f4
14-30 f4
Four batteries (charge 'em from solar or a weekly town stop)
Several XQD cards
iPhone with Lightning to USB adapter and lightweight XQD reader as a backup device (I knew there was a reason Apple has half terabyte iPhones). Besides being a lightweight device with a ton of SSD, an iPhone also has good LTE and WiFi - it can send the photos to cloud backup on town stops, and Verizon will regret the day they sold unlimited data to photographers - it doesn't get throttled because it's not on congested towers (and they are looking for people doing a ton of downloads, not uploads.
Solar charging rig or backup battery as conditions dictate
Before solar or backup battery, but including the four camera batteries, this is right around four pounds for near 4x5" image quality anywhere... It's relatively versatile - no long focal lengths, but I almost never do wildlife on multi-day trips (nothing vaguely carryable is long enough...).
For day hikes and other shorter trips, add some or all of (some rented as needed):
FTZ adapter
Tilt-shift lens
Gitzo Series 1 tripod
Long lens
True macro lens
For shooting events or other "in town" uses, any of the above plus:
A Speedlight or two
MacBook Pro
Little Canon Selphy photo printer (I have been known to use these to amuse my nieces and nephews at various events)
One could do something similar with any mirrorless system - my present Fuji system is organized along similar lines, and I would gradually add the higher-resolution Nikon gear as I could afford it. Easy adapter access to a big DSLR lens line helps for things like tilt-shift lenses, but Fuji, Sony and Micro 4/3 all have most of the lenses to do a travel plus in town system...
If the best primary body is as heavy as a D850 or a 5DIV, and the compact travel lenses aren't available, the "long hike kit" balloons from 4 lbs to 6 or 7, which is huge when your total pack capacity is in the low 30s...