Likely continue to dip until mid way through expansion cycle like around 7.3 or so. By then more "reliable" content will retain most active players, steady climb until the pre expansion lull hits with another dip. With the announcement of mobile version, seems SE is going a different route than what other companies would with player retention, theyre instead broading the playerbase with a wide net, would not be surprised if we do actually see a nintendo version in future.