CM did an amazing job on MyTeam and I love it so far. I truly hope they are going to expand on it in 2021 and here are my views on your points and some suggestions of my own:
-> More management elements like hiring engineers, strategists, mechanics would be great.
Furthermore: hiring department heads would affect how well each department runs. Maybe you could even try to "steal" e.g. a rival team's head aero engineer through negotiations much like you already can with drivers. (Imagine deciding on getting an Adrian Newey kind of guy to join your team to advance your chances the next season, but with the trade-off of a huge price and angering a rival team.)
-> More livery, helmet, suit, ... options would be the greatest thing, but I think we can all agree that CM isn't gonna let go of the Podium Pass / Shop system. That means we won't get a real editor anytime soon. They will want to bring out new stuff regularly as rewards or in the shop. This however shouldn't be a problem if they go with a customisation system like this:
underlayers for liveries, suits and helmets. These are basic shapes which can be colored and is pretty much the system we have right now in F1 2020,
extra overlay elements I would like to call "themes". These overlays could be used to give a real identity to your team as they can be applied over the basic underlayers of your livery, suits, etc. and tie it all together. These themes could be unlocked in the same way as the liveries do. One condition though: a theme is unlocked for everything (livery, helmet, ...) at once. Otherwise the whole point would be lost of course.
I'll try to explain with Mclaren 2019 livery and suit as an example (see below):
underlay: basic livery with orange, a black base, a blue back and a blue-black frontwing. The suit is blue with an orange diagonal.
overlaying "theme": the little triangle shapes that tie everyting together on both the car and the suits.
Other real life examples of possible themes: the little stars on the back of the Mercedes that helped keep their identity with the switch from silver to black or the iconic yellow nose on the Red Bull that has kept the Red Bull identifiable for more than a decade (although their liveries overal don't change that much).
Going into a new season you can decide to keep the general shape and colors, but make a subtle change with the theme (like Mclaren did in 2020) or you can change the overal color but keep the theme like Mercedes did. Both would result in a new livery that still connects to the same team identity.
-> I like the idea of developing your own engine. Also more fleshed out partnerships with other (bigger) teams to help advance your development would be cool. The wind tunnel is a great example! This would be really great for a startup team with little resources and who don't have good departments and department heads yet.
-> Other customisation suggestions:
more freedom in decal placement: scaling, moving and rotating + multi tone colors to better match your livery + customizing car numbers. Also more control on sponsor customisation on suits and helmets.
adding your chosen engine supplier, #WeRaceAsOne, Pirelli, F1 logo, etc. as decals to mix up your livery and look more in tune with the rest of the grid.
more options on you badge (combining them with more color variantion). Also having the badge shapes as decals (e.g. the Red Bull or Alfa Romeo logos on the side of their cars).
some sponsors want you to use their company colors (e.g. pink BWT Force India) but will pay handsomely if you do
-> Other gameplay suggestions:
more drivers from F2, F3, Formula E, reserve drivers, the Hulk, etc. The younger ones also evolve with passing seasons and join the F1 ranks more frequently.
reputation and relationships between you and other drivers, teams, engineers, press ... which will affect what contracts you can get, what engine manufacterers want to supply you, what junior drivers will be available, etc. The whole wind tunnel thing is again a great example of something you can only get if you have a good relationship with another team.
more random events and more challenges in later seasons. Examples: drastically changing regulations that "punish" the player (e.g. Ferrari's engine troubles in 2020), a bad sponsor that has screwed you financially (e.g. Rich Energy) or maybe even drivers gettin ill and be unable to drive.
other teams liveries change (slightly) between seasons as well. This could be a licensing nightmare though. Maybe the "theme" as explained above could vary a bit while their colors, sponsors, etc. stay the same througout the game?
being able to port your character and MyTeam career from the 2020 game to 2021. Maybe only allow a 1 season save or reset most development from a later save to keep balance?
-> Minor suggestions:
watch your race when you simulate
post-race highlights show the most interesting bits of all the cars. A new option "personal highlights" still only shows your bits.
