I don't think Mastodon is going to go away, but a federated Tumblr answers a lot of the annoyances I've had with it. It supports all the media types I want to post without complaint, and presents them each in a media-appropriate way.
If they can get it open source and decentralized, even better. This seems to be their long-term plan based on things I've seen in posts around the intwewebs. Making it WordPress-based is the goal, maybe as a major extension alongside WooCommerce and co.