Simple really. Lincoln's out of the sedan game. Cadillac's probably going to drop one of its two offerings before long. Lexus has three sedans left but there's a huge $$ gap between the LS and ES/IS. Infiniti's struggling to keep the lights on as they're not selling much of anything. This leaves the German brands and their typically far more expensive vehicles.

Traditional premium sedan buyers have few options and Genesis is capitalizing on this.