$84k starting price for the Land Cruiser is probably what the Grand Wagoneer will be compared to. They do have an alright luxurious interior though (super luxurious compared to Toyotas other vehicle offerings) but the front end of the cabin feels lacking. The rear isn't too shabby at all though.
there's not much else to expect from an interior in these vehicles just look at everything else being sold and you will find the same thing but what's more important is how well it functions, no doubt that this Toyota will take you everywhere and back, maybe further than the new Wagoneer
We'll most likely see something similar to what the Jeep Cherokee's cabin looks like. Simple and to the point, but with modern luxuries like the digital display in the gauge cluster and large infotainment screen.
I won't mind having little things related to the Grand Cherokee but it better be limited to things like the air vents and little parts bin stuff like that since the last thing they need to do is be cookie cutter with a flagship product. Here they can take on some risk by developing more Wagoneer-specific parts.
I doubt Jeep would move away from the Grand Cherokee all that much, simply due to how much it'll cost to develop new parts just for one model. May as well cut costs where they can and put the money towards more relevant areas like the drivetrain and architecture.
People will still buy one simply because of the Jeep badge, but they'll have to appropriately price it around the Land Cruiser because buyers may just go with Toyota if the Grand Wagoneer costs substantially more.