It should be supported for a while longer I imagine. If you like the core part of the game (physics) enough, I'd recommend selling your PS4 version and getting the PC one while it's cheap for a very cheap upgrade.
The mod scene is still active 3-4 years on with many, many high quality tracks and cars that the consoles will unfortunately never get to see. The same applies for extremely useful apps for the game. There are also a huge amount of poor quality mods too, but you'd have to venture away from the top recommended mod sites to find them. My AC garage looks like it came from Gran Turismo with the amount and variety of cars it has in it.
The PC version has an uncountable number of benefits over the skinny console releases, but it will only be worth it to you if you love the physics and can accept that there are still several missing features in comparison to other games. If racing AI is your main thing then I'd say don't bother, but if you're into track days, hotlapping and some online, you're good to go.
Another factor to consider is what components are in your PC? What's your CPU and GPU? With this info we can gauge whether you would have better or poorer performance than your PS4.