I would hope they'd use the 45W processors instead. I also don't see the G processors being used unless the entire line up were to use it. Making two separate logic boards probably isn't worth it. Seeing that there isn't a great deal of differentiation in the G processors with Vega I wouldn't hold out too much hope for them.
Also, given that they mention "Pro", I would hope that perhaps an i9 could be on the table. Given that they used them in the MacBook Pro refresh, perhaps that would be the processor family of choice. It would simplify their supply chain and allow for 6 core processors.
The other wish list item would be 10Gb ethernet. But I doubt the heat constraints would permit that. However it would feel more "Pro." I have no idea if they would keep Type-A USB or not.
I can see Kaby Lake-G much more easily than I can see Apple putting 45w H-Series in the Mac mini. The CPU runs quite quickly, finally gives the mini 4c/8t and a dGPU that can manage a VR workflow in a pretty small package...just look at Intel's Hades Canyon NUCs. If the price for the KL-G is on par with the price for an H-Series CPU, I know which way Apple is going. I believe the 21.5" iMac will be the recipient of any 6-core CPUs at this point (Coffee Lake 8th Gen), while the 27" iMac receives 6- and 8-core 9th Gen CPUs. This creates pretty clear delineation in the product lines.
10Gb Ethernet in anything other than the iMac Pro and MacPro is at least another 3-4 years away. There simply isn't a large enough user base clamoring for it in any meaningful way. If you have a FiOS connection, and you are hardwired, the current 1Gbps Ethernet works just fine. For the iMac Pro and the Mac Pro, it makes perfect sense, they are Pro machines that will need to be in a Pro workflow, which means 10Gbps Ethernet for a lot of folks. Also, if you own any other Thunderbolt 3 equipped Mac and
really need 10Gbps Ethernet, there are fairly economical options to add it to your setup (standalone or in a Dock).
I think Apple will leave the port configuration pretty much the way it is, as Kaby Lake-G has x8 PCIe lanes left, so at 2x4, this allows for one Titan Ridge Thunderbolt 3 controller and the PCIe storage to connect directly with the CPU and the rest of the computer (Serial ATA, USB-A, SDXC, HDMI, 802.11ac Wi-Fi, Bluetooth 5.0, et al.) to communicate with the CPU via the PCH. For ports, I predict one Gigabit Ethernet port, HDMI (50/50, needs an LSPCON for HDMI 2.0, may get dumped), two TB3 ports, four USB 3.1 Type-A ports, one SDXC, and two audio jacks.
If Apple chooses the Core i7-8809G, cools it properly and gives it a semi attractive price, it could be a real hit. The clock is ticking.