Backing up journal entries to Dreamwidth is easy-peasy, but there's no Scrapbook importer - on Dreamwidth or, as far as I know, any other site. (If I'm wrong about that, please let me know.)
Whatever happens to LJ - and I hope it'll be around for a good long time (after all, MySpace is still kickin' and sent me an email just the other day) - it's a good idea to always back up your data.
I did some poking around, and this method seems like the quickest and easiest way to save all of your photos. (The recommended extension, DownloadThemAll, is/was Firefox-only and is no longer supported as of December 2016, but you can always right click » Save as… every link.)
Hopefully that saves some headaches.