Since there's some confusion in the tags:
Tumblr is starting to actually sunset it seems.
The site will still be basically functional but we don't really have a way of knowing for how long.
It could be months or years, but overall functionality is going to start going down. The staff is being cut down to a skeleton crew.
Here are the threads for The Post:
It's time to start coordinating on where to go next.
Tumblr had just recently started up when Live Journal was sold to a Russian company so this is where most of LiveJournal ended up and that was on purpose. People chose as groups to come here.
(LiveJournal was where most of FF.net and a fair number of deviantart artists had ended up previously when those sites had been losing popularity and having issues)
Honestly though it's been a nice decade plus here and I guess nothing lasts forever.
It's time to start archiving your blog, archiving your favorite blogs run by other people, and setting up new accounts to put everything elsewhere.
With Black Friday around the corner now is a good time to buy some flash drives or other storage for your backups.
Maybe make a youtube video of what your blog/favorite blogs look/looked like while the site is still functional to remember them by.
People will begin to discuss the merits of various platforms/websites and compare and contrast them and give them a trial run while keeping their account open on tumblr for a while.
Different communities will have different needs. Tumblr really was amazing because it catered to so many different styles of expression and because of that so many different kinds of communities could make a home here; but most sites aren't really built like that so that's where people may find some sticking points.
It may mean that we won't have a one-stop website for everything that we have a niche interest for anymore and instead have multiple sites for different things.
And of course there will be things (probably distinct reblog chains and tags scrolling / note scrolling) that only Tumblr did unless the new sites incorporate that into their design.
What's great about the fact that we were given the info now is that we can coordinate where to go to a certain extent.
Tumblr being built the way it is has fostered a lot of unique interaction but at the end of the day it's still the community and comraderie that makes this place home.
If we coordinate where to go then we'll have an easier time getting started there.
I do feel extra bad for all the recent Reddit and Twitter influx because while I'm sure you all knew you were running from a burning building into a sinking ship, no one knew quite how fast we were taking on water it seems.