Just read the interview, great news!
In GT7, the time and weather will be moving in real time.
The weather simulation is actually a weather simulation, not just a weather change. So it does have an effect on the physics of the game. I think that will be very interesting. And also you can set multiples of the time that it takes from real time to 100 times accelerated, so you don't necessarily need to have a full on endurance race in order for the player to experience those weather changes and how it affects their cars in the track.
We don't have a system for simulating the amount of rubber that's laid on the track, but we do have a simulation of where the rain would create a level of water over the track. When a car passes over it, it will spray aside, and so the racing lines will dry quicker than the other parts of the track. That's something that is simulated and does affect the grip of the course accordingly as time goes on, and the track begins to dry in different places. The air temperature, the humidity, and then the road surface temperature will also be affected by these weather changes as well.
As for differences between the ps4 and ps5
Feature wise, they will be the same, but the quality that you'll be seeing will be different.
Cross-play is confirmed.