What bothers me about the queue less system is that I can't see it work well when it is really busy. When it is really busy, you immediately notice it because there are people everywhere, giftshops and eateries are filled with people just as the attractions are, so are the streets etc.; so if we also take away the queues, then that means even more people in the streets, shops etc.
Also, granted no one likes to wait in line, but queue or not, you will be waiting; now if it is just one wait for your virual queue, that's fine, you go and eat or check out some gift shops etc., but if everything becomes queueless, well, how many time can you spend in the giftshops, restaurants etc?