Take some advice from those of us who used Yahoo products for a while: move to a good platform. Wordress.com is good.

If Yahoo lives up to its past, here is what will happen to Tumblr:

1. Yahoo will gradually try to their other products into it, or it into their other products somehow. They'll decide that the users want something different to what they chose to use and begin a slow plod towards something nobody wants. It will be buggy and unstable. If you complain loud enough, they'll tell you that Yahoo knows better than its users what its users want.
2. In nine months they'll realise that have completely failed to gain users or do anything interesting, and will begin to get bored with it. The half implemented changes will stay half implemented.
3. In 12 to 18 months they'll announce that it wasn't what they wanted to do after all. They'll announce no further development will occur. Bugs will suspiciously start to appear. Reliability will go down the pan. You'll have to refresh your page four times to get to the right content.
4. In about three years they'll eventually pull the plug. Probably at short term notice, giving nobody adequate chance to export all their content. If you're really unlucky they'll rub salt in the wound by launching a half-hearted alternative that's too rubbish to be useful to anyone.