The new not so great firestorm is there and if you want to or not you will be forced to update because they are blocking older versions from connecting to SL.
Important note for people with RLV items:
This version of firestorm is bugged and many RLV commands do not work like they should.
If you are using any RLV products it is recommended you downgrade to a older version of Firestorm until a new version comes out that fixes these bugs.
The older versions can be found here:
https://wiki.firestormviewer.org/fs_older_downloads