SUV is definitely the trend to go. Lexus used to have the most SUV models, but nowadays most competitors have at least the same numbers of SUV if not having more in their lineup.
I would say that using the new platform of LC500 to design a flagship unibody SUV will not only give Lexus a good possibility to generate profit, but also can lift the brand recognition to another good level. The aim should be high, the big loaded Range Rover is a good reference.
Then, a 3-row crossover is the way to move the bigger number in sale. It must be quite difficult to design a 3-row people mover like a true SUV. Those MDX/new Q7/GL just look like minivans on diet to me. Lexus please try harder, and show us a better one when it comes out.
For GX, there must be some lessons learned. One of the things is that most people paying big bucks for a luxury vehicle don't want to be looked as homely boys. BoF GX is unique in luxury SUV now, especially considering its size. Still, people want that. The next gen should be quite easy. I would say that a inch wider/a inch lower/1-2 inch longer with another quality interior and an evolved exterior. A de-tuned 5.0 V8+8 speed=next GX500
Lexus has its own experience and success, and should not chase the same game as German, instead focus on its own established styles which are the core values of Lexus owners looking for.