There is no evidence to suggest that they are ever going to come back. I am not sure why you think that only 25%-30% of the people who have played the game are still playing is a good thing.
Free to play games still make a profit and LoL has even larger player base than WOW, but that has nothing to do with the topic of the thread.
If you think the topic is meaningless then why are you here? Do you even know what the topic is? You haven't managed one on topic reply yet. Maybe you could go an derail another topic?