There is no punctures and won't be. There will maybe be more of a performance drop off. Not a problem, you just have to pit earlier if that's the case.
If it's easier to wear the tyres (I mean, wearing the tyres up until the drop-off point) I don't think it will be a good physics update. If you are on a cheap wheel or controller you are already quite disadvantaged by the current tyre wear across the lifespan of the tyre.
IMO the biggest issue is that there is a lack of feel in GT compared to other games ever since update 1.15 where they killed off the force feedback and it has felt inferior to GT Sport ever since. Cars just snap with no warning so it isn't like what they have right now is for the masses.
Also the tyres getting dirty is way overexaggerated compared to other games like ACC.
Hopefully the physics update is good, because the issue with the game isn't the lack of cars, it's the fact that so many cars just aren't that fun to drive, and the options are limited.
Eiger Nordwand was cartoonish and fun with shuffle racing, but it's going to suck with spec series or overtaking people as is. It might be enjoyable with the plodder AI because there's always corners so you're not bored, but if the physics update isn't up to scratch then anyone who plays online is going to be disappointed