My bets (these are based on "narrative needs"). Basically, the first movie will do two things: demoralize our heroes and emphasize how powerful Thanos and the Black Order are. I expect it to be nothing but
throwing rocks.
Part 1 Deaths - Vision, Ramanda (T'Challa's mom), Nebula, Rhodes (War Machine), an Asgardian (more likely Loki), Hawkeye.
Part 1 Incapacitations/Missing - Drax, Groot, Steve Rodgers, Thor (if not dead), Falcon, Bruce/Hulk, Scarlet Witch, Gamora, Strange, Rocket, Gamora
In the end of part one, the only "fighters" left will be the physically or emotionally "weakest" ones: Tony, Natasha, Peter Parker and Quill, T'Challa, and Bucky (Mantis too). The post-credit scene will be between Nick Fury and Carol Danvers, discussing the need to get back in the game.
Part 2 Deaths - Steve Rodgers.
No really. I think that'll be it. Part 2 is assembling the Avengers. Steve will be there. He and Tony have to fight side-by-side in the ultimate climax. When Tony tries to sacrifice himself, Steve does it instead. That'll be enough to send Tony into hiding, removing him from the MCU while allowing him to reappear in the future.