This instagram horse has been beaten to death. Let us give Eyem a go. It's cross platform and a pretty good replacement IMO Just no one is on it. Clearly instagram doesn't want us there so let's make our own party! Don't complain, contribute.
I've actually been checking out Fhotoroom, which is almost an identical, drop-in replacement for Instagram. It has more filters, posts to the Fhotoroom network which is just like the Instagram network with all the same features (likes, hashtags, etc.) and also posts to FB, Twitter, and others. If we're (meaning WP users) going to create an Instagram replacement, my vote is for Fhotoroom.
Lomogram!