Weight may be an issue... Its a big camera. I like the way a D850 fits my hand, and would use a vertical grip anyway, so its not much of an issue to me (though I haven't bought one yet)
Wait on the other hand is now a non issue as they are in stock in quite a few places right now.
Wallet is what I can't get passed just yet. Its an expensive camera for my budget. If the Z8 being a "baby Z9" turns out to be true, I'll likely buy one of those, but I'll miss the battery grip and probably wish I'd bought the Z9, lol.