Very nice, that's a huge improvement. Dynamic tracks will make it harder to pass, harder to be consistent and it will punish your mistakes more. Yet, I don't think those are bad things, some people might be unhappy about the effects but in the end it simulates real life situations that make sense to have in a simulation.
I suspect they want to release dynamic tracks and time-of-day transitions at the same time because of the dynamic track temperature which makes less sense without a moving sun.
I wonder though about those marbles. He said they get displaced when cars drive over them. Does that mean they will stick to your tires and actually unbalance the ride and decrease grip when stuck? And it would be really cool if you would have to weave around to get rid of the marbles again.
I also can't wait to see and try out the effects of this in endurance races where it will probably matter most.