The R8000 uses a BCM4709A0 ARM CPU which looks like it might work using bcm53xx.
The R8000 has three radios all BCM43602, one 2.4GHz and two 5GHz.
AFAICS there are three supported PCI Device IDs for these radios all supported by the brcmfmac mac80211 driver, 14e4:43ba from 3.17+, 14e4:43bb (2Ghz) and 14e4:43bc (5Ghz) both supported from 3.19+.
I also 3.19 is slowly being used in the openwrt truck.
Is there a chance that this will work some time soon or that someone could work it or perhaps point me in the right direction?