I'm guessing that with the fickle computer-controlled fine tuning that today's super-high-horsepower machines need to stay ahead of the competition, the high-revving, low torque Wankel engine would be quite unsuitable in today's racing environment?
It has been around for many years now, and I would have thought that if it ever had any advantages they would have been recognized/utilized by now.
As for road use, I don't think there is a large enough motorcycle market for them to be viable, and in the automobile world I think emissions are the biggest stumbling block, plus in today's apparently successful turbo-charger fad for more horsepower from smaller engines I don't think the rotary engine could get a look in.