Just FYI, there are apps you can run to make local backups of all the image / video posts for which you've ever clicked the "Like" button.
One example is this set of precompiled executables for mac and Windows. It's not extremely user-friendly, but after some monkeying around, it seems to work for me, it's happily grinding away filling my hard drive. Any of these apps use Tumblr's API which rate-limits you to 1000 downloads/hour, 5000/day. I hope the app is smart enough to wait and resume if it hits any of those limits..
I for one will miss these curated streams of porn / erotica, special interest themes, and discovering new types of porn I didn't even know I liked. There isn't much else out there quite like it. According to other posts, Yahoo paid $1.1 billion to acquire Tumblr, then was eventually subsumed into Verizon. Speculative posts are either humorously noting that Yahoo is killing yet another company from beyond the grave, or noting that Verizon hated Tumblr and now Verizon Oath is tasked with dismantling Tumblr, or at least killing off the troublesome annoying parts of it (ie. porn). Some stats from several years ago suggested that porn was only a small percentage of Tumblr's content, but general consensus seems to be that this had increased considerably. I guess soon enough we'll see what remains in a post-porn Tumblr world..
Anyways... Summary: There's a link above if you want to locally archive your favorite Tumblr pics/vids, before they all become flagged / inaccessible / deleted / whatever.