I'm befuddled that Automattic is still investing in adding features (e.g. federation) to Tumblr. There's just about no chance of them actually making money from it, because its users are just about the most monetization-hostile users on the Internet. It doesn't help that the CEO actively antagonized a large portion of the site not too long ago.
If they're converting Tumblr to Wordpress, I bet it will get folded into their main hosting solution eventually and Tumblr will cease to exist.
The public blog network is a minority of traffic. If you've never actually been a Tumblr user, you won't have an understanding of the product at all.