And PCARS has dynamic weather and day/ night cycles
So i'm sure T10 can follow suit.
I'd like to think so too, but your forgetting that PCars has yet to prove itself as a premier sim racer that can stand toe-to-to with the likes of Forza/GT franchise, and the implementation of weather/dynamic-time-of-day would also have to be best in class. I've played the pre-release versions of PCars on PC, and to me it's not a patch on Assetta Corsa physics/tire handling models. It sure is the prettiest of them all, but you need a serious piece of PC kit to run it any anywhere near 60fps locked. Unfortunately, even with my SLI 760 setup, I can't get a consistent 60fps, hovering in the 35-45fps range. On the other hand I get a locked 60fps on AC. Until I can play PCars at 60fps, I cannot be sure it is even in the same league as Forza/GT.
Moreover, on XB1 PCars is likely going to land at 900px60fps. This means T10 would have to implement weather/dynamic-time-of-day whilst maintaining that 1080x60fps native output. Again, not a easy thing to do, considering the hardware constraints.