I really like a lot forza franchise but for me has 3 main areas of improving:
A secondary or alternative Story mode:
Career is good, much improved from lasts entries (forza 1-3 and 5 career modes were awful!), but I rather prefer an optional (do not remove actual single player mode) story mode a la F1 or Project cars too! This means that forza Should have a single player mode and a Story Mode (Embrace your Dreams). You can even use names of drivers in horizon or pgr as rivals!
Race inmersion: trainings, qualifying and races with full pits.
Replays:
https://youtu.be/A6ghtWCVL1Q
I watched this and man, looks outstanding, made me wanna buy a steering wheel, a ps4 pro just for feeling the inmersion of being in a race.
For other things, Forza is an outstanding franchise and Forza 7 is a great game. I own every Forza except 2 (and every horizon and PGR).