21K AWD 17 stock
POTENZA RE97AS RFT between 7/32 and 8/32 thread left (new thread depth 10/32")
If you keep tires properly inflated (35 cold) and rotated each 5k or 6 months (whichever driving style fits better) - you will be fine by end of lease. Especially if you lease another Infiniti since you will get $500 tear waiver credit.
And you are correct - RFT equipped cars MUST be returned with RFT tires and do not listen to anyone saying otherwise - you will be taking huge chances attempting to return non RFT and not get hit with surcharges. (some people get lucky once in the blue moon though)
Also keep in mind that tread wearing FASTER on NEW tires - the less thread left the SLOWER it will wear.
P.S. And I drive like maniac - so I am really surprised to hear stories from people that they need new tires or brakes after 15K LOL