Niantic has been steadfastly making improvements to Pokémon Go since its launch in July 2016, switching up gameplay rules for a better player experience, adding features such as dynamic weather and pushing for more hardware specific features in its AR component. So it makes sense that if it wants to keep driving the game forward it'll have to cut loose some dead weight. There's no word yet on a similar move for Android users -- perhaps Niantic is testing the waters to see how this cull affects its user base. Support will be removed via an update rolling out on February 28, so upgrade now if you want to keep catching 'em all.