When most people look at sports car purchases, "sense" is usually not one of the driving factors, especially if the car happens to look as gorgeous as this concept.
Gas mileage is awful with the Wankel. That goes without saying. That said, most of the failures on the RX-8s came from the first generation of the RENESIS - saying that block certainly had problems would be an understatement (the ECU needed reflashes galore, for starters), and compounding it were the automatic models only having one oil cooler instead of two, a tremendously stupid decision considering how rotaries dislike excessive heat. The 2009 and on models fixed all those issues, with the failure rates being astronomically lower. Plus, the choice of oil really does matter - to quote someone else on the subject:
"For those who are familiar with the regular rotary heads on the various forums, the weak link in the Renesis, as with all rotaries, is the apex seal, and the potential for problems in this regard can be dramatically reduced by using a appropriate weight oil, keeping the oil filled towards the high end of the dipstick at all times, and regularly flushing and filling the coolant, which all help to ward off heat related issues and ensure proper lubrication of the rotary internals (many of the long time rotary-heads premix, too, and that’s a carryover practice from the days of the RX-7)."
I'd look again on the used market. The RX-8s selling for dirt cheap are generally from the 04-08 run before the 09 makeover, and for good reason.
I get that it's not a car for the mainstream, but let's face it; if you love the rotary driving feel you're not getting it from anywhere else (shifting at 7000+ RPM as a part of maintenance? Yes, please!), and I'd like to see what Mazda's got in store for a potential RX successor. Who knows? The SkyActiv-R could just be straight-up marketing BS, or they might have something of substance with this new incarnation. I just love how in the background, with the Miata and Mazda 3/6 at the forefront of their brand, their engineers are still tinkering away with the rotary, the little engine that could. Zoom zoom.