It's sort of amazing there hasn't been a game like/as good as Burnout Paradise...since..well...Burnout Paradise. I suppose I could simply go back and play it if I want a game like it but I sort of got tired of the Paradise setting after a while. Forza Horizon is making a big mistake not including a seamless open world setting with always connected online play.
I'm sure they have their reasons for doing it the way they are. There is no traffic in the online modes as well, so it would be odd to pop back and forth between online and offline quickly.
I'm a huge Burnout fan and I loved Paradise; if you're looking for a Paradise kind of game, then NFS Most Wanted, Criterion's next offering, comes out soon after Forza Horizon. You may want to look into that game because it looks like it will share a lot in common with Burnout Paradise. I'm just getting both games though, they offer different experiences that are both great.
TDU is - or was - the same way. The open-world freeroam was like a giant road-system lobby. I didn't know that was the case with Burnout Paradise until I had a head-on with someone, both of us in Hunter Rally carbon...thingies...