Not necessarily. The Z has been sharing a luxury car platform since the 350Z.
While the 400 hp Q50 Red Sport 400 starts at $51k, the 300 hp Q50 Sport starts at $40k. The dynamic suspension is part of a $1500 package with "sport brakes" and paddle shifters (though in typical Japanese car fashion they force you to get another $2500 package in addition to it). There's a $4k difference between the Q50 Sport and the Red Sport when the Sport is given the packages that the Red had standard. I doubt that the Red Sport has anything more than a slightly larger intercooler and slightly larger turbos. That's maybe a $5-600 parts price increase for an OEM. The rest of that 4k price increase is sweet, sweet profit.
Of course, that's going from smaller twin turbos to bigger ones. Ford charges an extra $1000 to go from a 3.3L V6 to a 2.7 twin turbo V6 in the F-150. AFIAK, the 2.7 is using the same K03s as the 3.5 F-150 Ecoboost. Nissan will still need to do model specific durability testing and suspension tuning, but a lot of the difficult work is already done.
Interior wise, Nissan doesn't need to go full on luxury car. They just need to step up to what Mazda's doing on their Grand Touring package cars. If Mazda can do it, Nissan can do it.
