Normally, wingsuit jumps end with a parachute deployment. But the last time I looked, a fellow was trying to figure out how to flare and land without a chute, just using the lifting capacity of the wingsuit. He may have given up by now. I doubt it is possible, but you could certainly get killed trying. Perhaps one could calculate a flare factor — the product of lift-drag ratio and wing loading, with suitable exponents, required to permit a given touchdown speed — in order to know what kind of wing would be required to allow a man to touch down at, say, 25 feet per second with a survivable vertical velocity. Hang gliders do it all the time, but a hang glider is a far cry from a wingsuit.