Guy’s calm your tits.
If it really was a big fucking scam I think Tumblr staff would have caught on by now and posted a public service announcement about it to protect all their users. I really doubt this is a thing that flew completely under their radar given how fucking popular it became when it was announced.
I think you should all calm down, drink some calming tea or something and wait to actually see what happens rather than freaking out on launch day because the application is having a few issues.
And if your tumblr IS deleted or whatever it’s not the end of the fucking world. Most people have any private information that’s contained in their accounts posted on their fucking blog anyway. It’s not like someone can steal your identity with tumblr unless you were already doing something stupid. Which is what most hacks and scams (particularly fishing ones) are aimed at, unless it’s one just to cause disruption.