Slim-to-none chance of official support, but SMS unofficially are OK with mods and there are backdoor workarounds in pCARS 1, albeit ones that require much hoop-jumping. It's nowhere near as easy as drag-and-drop modding in Assetto Corsa, for example.
Actually OP, your best bet right now is Assetto Corsa. It runs great, has class-leading AI, FFB and car handling. After several patches Project Cars 2 will hopefully realise its potential to be one of the best motorsport games ever made, but right now Assetto Corsa could be your best option.
Does Assetto Corsa still have a decent online community? Which one is bigger: PC or PS4?