Renderings and rumors of the GS F have been circulating since last year, but word came down in August that Lexus planned to delay the introduction of the 500+ hp sedan due to the economic downturn and the (then) high price of fuel. Add that to the possible cancellation of the LF-A, and things aren't looking good for Lexus' foray into the world of high performance.
If an LS F model would come to market, only a few drivetrains could be fitted to the hulking sedan to give it the level of performance necessary to carry the F badge. If Toyota does decide to build the LF-A, its V10 powerplant would be a great candidate for the LS F to provide motivation and defer some of the costs of the supercar.
According to two Lexus execs we spoke to, the IS F outsold both the Mercedes-Benz C63 and BMW M3 Sedan last month (we can't confirm, since Lexus doesn't break down sales of the IS by model), but if consumers are accepting the idea of a high-performance Lexus, than other models will surely follow.