These are just a few suggestions, that would of course take plenty of time to add, and may not be added, but what I would like to see.
1. Update the British GP course.
2. Add tracks that are ran in F1 today (USA, Mexico, Canada, Russia, Azerbaijan) (Eliminate Turkey)
3. Ultra soft tires.
4. Limiting what type of tire can be used on each track (example: Monaco: Soft and super soft (and ultra soft if added) and Spain: Hard, medium, and soft, and so on with all tracks)
5. Bring back the marketing building, to produce more money.
6. Increase sponsor pay out on either bonuses or base pay (preferably both)
I know these would take a while to add, and may not be added at all, but I believe that this would make the game much more realistic, and more enjoyable.