This answer was to be expected. No Lexus management member is allowed to discuss future product plans in detail, so it is quite normal that Katsuda-san doesn't reveal any 7 seater plans.
However, if market request is real (and I believe it is - certainly if it comes from the brand's biggest market), then why shouldn't they plan a 7 seater SUV, based on the underpinnings of the RX?
Remember the statement from Bracken last year:
“Third-row seating is the No. 1 issue we hear from dealers,” Lexus Division chief Jeff Bracken said at the auto show here. “We feel like we’re missing a 35,000-units-a-year opportunity. We’re working hard to rectify that.”
“It could be any number of solutions,” Bracken said. “We could bring it to market in 2016 or 2017. If we can get it, that’s the priority. We won’t be bothered if it steps on RX. We want it.”
If the request from the U.S. is that strong, a 7 seater SUV should be closer to market than Katsuda-san pretends. But I am also convinced that the camouflaged RX test cars that were spotted recently in different media are 7 seater prototypes.