I think it would be cool to have some basic customization options for your driver and the possibility to exit your car in the future installments of the Horizon series. Looking at all the demo gameplay videos in Youtube at the moment have these crews of players hanging out, parked somewhere while one player flies around with the drone... And it looks a little bit weird that all these people attending a festival just sit around in their cars, looking forward, both hand on the wheel :D
It's not something that would take away too much resources from the development, as I'm sure Microsoft has some assets in their possession to have individual avatars with a walking/running/emote animations to get the devs started, but it would to A LOT for the immersion in the game. Imagine walking around a car meet, being able to open other people's car doors, to look at engine bays etc. Or having a clubhouse/garage for your crew to hang out in, with all your cars on display.
I'm not talking about a pseudo-sims trainwreck like TDU2 was, which forced players to do this. This system should be completely optional, so that people who just wan't to drive around can do that without even menu prompts telling them to customize their character etc.
I genuinely think a player character with basic customization options and possibility to exit the car is the logical next step for the series and to be honest, I'm quite sure we will also see it in the future.
Inertia creeps