Let me start off by saying good post.

When it comes down to it, I think people who are looking to buy a full sized luxury sedan are well into their 50's a lot of the time, and prefer a more cushy ride and the more conservative styling the LS430 has. Not to mention the Lexus name.

I would hope to see an RL that has a 3.5L V6 (J35 would do just fine) powering the front wheels and a eletric motor for each rear wheel. Otherwise I'd think there would be too much weight at the front, and too much torque for the front wheels to handle.