If you are wondering, what would be the effect of a six core versus an eight core processor on the game? We'll lets test just that. I have one quick chart I would like to show you, the results below are based on default clock frequencies aside from one OC on the 5960X to show you the difference when you tweak a lower clocked processor..
* Core i7 8700k results have been retested and re-published at 6:18 CEST Oct 25th. When I setup the Z370 / 8700k test-rig I performed a CMOS clear which enabled an ASUS Turbo optimization (the infamous all-core turbo optimization) at default. This has been manually disabled again and the test re-done. We always perform our tests with Turbo enhancement disabled as that is the Intel reference setting.
Especially at 1080p with a card as strong as the GTX 1080 Ti is there's more to gain from a nice processor tweak. I also included a result of the test setup with the proc at default and overclocked (all-core) at 4.2 GHz. Destiny 2 really likes faster clocked processors, and wherever you are not GPU bound, that will show. Mind you that with a Vega or GTX 1080 or lower card these 1080p offset differences are much smaller as there you'd be more GPU bound as well.