Sega Europe has finaly released DreamKey 3, it is available to order from the DreamArena website.

Quote from sega-europe.com
Dreamkey 3 enables you to choose your own Internet service provider (ISP) and it’s essential you order a copy if you want to continue using your Dreamcast online. Remember, from March 1 you will require Dreamkey 3 to use Internet, email and chat – it replaces the current disc you use to log on.
End Quote

Thanks to Gmc for the news.