GS400/430 are indeed a truely fast car. Needless to say, its handling, acceleration are superior. However, I personally thinks that it is still as competitive as BMW's 540. Maybe, it can outgun some some sport coupe such as Integra-R or RSX-S even its own cousin, Celica-GTS on 0-60 acceleration. However, there is also other parts of story. On the track, or even just the nifty road of the mountains, can GS still be as nimble as the others? I seriously doubt it. Sure, it is fast and luxurious but it is a must in its competition. Look at Bimmer's 540, MB's E500, Audi A6 4.2 or even our TL-S, they all have similar statistics like sport coupes on just straight line acceleration. Nevertheless, when you talk about track ablity, everyone here would tell you that those coupes I mention would do so much better than GS. Speaking of performance in this class, the only car I would think of right away is M5. Massive acceleration, incredible handling and unbelievable luxury. If GS is an all-star in its team, then M5 is an all-star in all the all-stars. Though, now, there are RS6 and E55 who are as good or just better than M5. Therefore, GS is just not a performance car and my thought towards GS series: A very Sport Sedan.
On the issue of MR-S, Supra & XX00GT, I believe if the later 2 show up in the near future, Toyota definitely can let the 3 live together for a while (not just mere 1 or 2 years, but like a generation or 2). Here is my reason. 1st, Toyota moved MR-S to roadsters so MR-S is already not targeting the people that Supra covers. 2ndly, Supra used to be a Z competitior, I don't think this time he will miss out too. With Z shifting to the demand of mid-level die-hard hard-core player so does Supra. Lastly, what a XX00GT will be aiming is most likily the purists who are looking at GTR, NSX, 360 or just 911Turbo. Say there is a Supra GT coming, I would say it is like Camry XLE V6 and ES300. YES, it feels good but once you sit in ES300, you know you are in a different class. Therefore, I highly think Toyota will let them all on the market at same time.