A7IV would be unlikely to have 10bit internal. We’ll be lucky if the A7SIII has it. “Lousy” weather sealing is some silly nonsense gear-heads and measurebators talk about. I’ve shot a plastic NEX5 in light rain, had a D7000 splashed (and me soaked head to toe) by waves at the beach, and a shot a D50 in a literal sandstorm in the desert…all fared just fine, none were remotely weather sealed.
If you spend your days making clickbait youtube videos pouring gallons of water directly onto your camera then I could see it being lackluster in that regard, but for most people save for a few NatGeo types who spend their free time in the rainforests of Borneo I think the Sony (and just about any brand) bodies are fine for the majority of usage.
But sure, go buy a Z7 if you need 10-bit internal FF today. A GH5S would be good too if you don’t need FF. Again, I wouldn’t bother waiting on the A7IV as best case scenario it’ll have 10bit, but you’re still waiting 3 years…or worst case only the A7SIII has it, and who knows when that is coming.