This is not so much a problem in the US where crossing other than at intersections is not permitted (and hence there are other disincentives to cross), but in much of the world no such regulation exists.
It is likely that this behaviour will not result in injury given the sophistication of the driverless car technology. However it is likely to result in traffic and a decrease in efficiency of the road network. As such it might be expected that crossing laws outside the US begin to follow the US model.
It is notable that this behaviour is not likely to emerge until all cars on the road are driverless, which will likely take some time.