No, read again
What codehound said was that LFS is between GPL (worse) and iRacing (best) in terms of feeling what the tyres do. I cannot say how accurate GPL's tyre model is in comparison to modern ones. You have to keep in mind, though, that GPL models a completely different type of car with the completely different bias-ply tyres (which are very stiff and have almost no sidewall flex), so I don't think a 1 on 1 comparison is fair in that regard. That said, I think people have a bit of a rose-tinted-glasses issue going on when saying that GPL is still the most realistic sim out there. Maybe the one they're most accustomed to, but realistic? Well, who knows, different car and all that.
In regard to LFS, what most people say they feel is wrong is the way tyres lose/regain grip - it seems to happen too smooth, too gradual. So if anything is going to change then I'd say it's rather going in the opposite direction of GPL-like smoothness. However, we don't really know anything about the new tyre model, other than what Scawen said and that the beta testers approve of the changes.
One thing I'm fairly certain of is that the new tyre model will have more load sensitive tyres, since that is from my understanding of tyres the only thing that would fix the issue Scawen described (too much grip on outer wheel, simply reducing grip won't fix it but would only shift at what speeds the problem occurs). By increasing the load sensitivity, the outer, loaded tyre would work less well than now, resulting in a more equal spread of how much the loaded tyres provide grip compared to the unloaded ones.
This should have a quite profound impact on how the cars feel and more importantly how they have to be set up to drive well. First, anti-roll bars will have more of an effect and the effect won't be the opposite from what you expect. The stiffer end of the car would then have considerably less grip, since the loaded tyre (which in a corner also bears some weight of the soft end of the car) wouldn't be as grippy as now. Second, the way differentials work would be vastly different.
Right now, having low-medium locking diffs is not feasible for the most part. Such a diff works rather poorly in corners, since most grip is on the outer tyre whereas the inner one barely contributes and easily starts spinning, taking away power from the outer wheel. For the same reason, high locking or locked diffs don't cause nearly as much turning problems as they should. Again, the inner tyre barely contributes, meaning the tyre that should normally fight against turning the car just sits there doing nothing. The currently fastest setups exploit both these deficiencies to their full potential. On one hand, they use locked diffs (or clutch pack diffs with 800Nm preload, claiming it feels better/not being a locked diff exploiter, ironically without realising that at such preloads the diff is for all intents and purposes locked), granting them full power even when the inner wheel is in the air. On the other hand, they give full ARB strength to the end of the car with the locked diff, causing all the load to go to the outer wheel (sometimes even lifting the inner), reducing the negative impact on turning to zero. This is mostly done on FWD cars, but really all cars "suffer" from high locking diffs being too viable. Overall it would be more important to make the inner tyre do some work, as the outer tyre alone would be much less efficient than both tyres working together.
