The biggest concern here is that if Section 230 is struck down by the court, it would mean that in order for any online content provider to be compliant under a S230-less Internet, ALL user-submitted content would need to be manually and individually reviewed prior to it being publicly viewable, lest the provider be held liable for what that user said/posted. It would mean the end of YouTube, Twitter, all fora everywhere (including Halforums!), every comment section, and possibly the end of every streaming service as well, since this would technically mean that, for instance, Netflix could legitimately be sued for allowing users in more restrictive locations to use VPNs to connect to Western exit points in order to watch content not available in their country. And more.
--Patrick