According to this article [1], you plan to move Tumblr's backend onto WordPress. Considering that Tumblr's infra stores over 1 trillion distinct product objects, this would be one of the most technically ambitious migrations in history. Can you share any thoughts of how it will be approached? Will you be pruning/purging old content or inactive users?
[1] https://poststatus.com/automattic-has-purchased-tumblr/