It's a real shame that Hank and Jan's characters were both wasted in the MCU. Although I do think that Stark creating Ultron ended up working pretty well especially after his PTSD with the Chitauri but the absence of Hank and Jan on the Avengers meant that the comics had to follow suit. That's cool that Viv is getting almost as popular as Wiccan. I've heard that Wanda/Vision is taking a lot of inspiration from the Vision series by Tom King so Viv might not be out of the question. If Simon makes an appearance, I wonder if the Grim Reaper could appear as well, perhaps as a manifestation of Wanda's fears especially considering all the death she's seen in her short life.
I forgot about War Machine to be honest. He's always sorta just been there but never contributed much so I wonder if a Disney+ series for him would really be in demand. I agree that Hemsworth and Hiddleston will likely be done soon and same for Rudd. Evangeline Lilly hasn't been around long but frankly her Wasp never really hit it off with audiences so I can't see her becoming a mainstay. I wonder if they'll even bother with future GOTG films if the entire old cast is gone unless the third film is meant to introduce new characters like Adam Warlock who will take over. I suppose Carol Danvers could become the new leader of the GOTG as well. From what I last heard, Tom Holland can do one more film for the MCU (Spider-Man 3) but I think that might be it for him. However, I wouldn't be surprised if they alter the deal again in the future so he can stick around longer because he doesn't seem even remotely done and Marvel doesn't seem like they want to lose him. Maybe they'll phase him out with Miles Morales though but Miles will have the same issues as Peter did with being a Sony property.
Yeah, Pietro and Speed have a lot in common as Pietro himself learned in Children's Crusade. I've heard that Magneto's origin will be changed so he won't have been alive for the Holocaust anymore.