Very huge news.
For some context, SLS has 3 versions: Block 1, Block 1B, and Block 2. Each one is stronger than the last but also more hypothetical. Originally Block 1 was set to launch just one time as a test mission, and then Block 1B would take over. Block 2 would eventually take over around 2030 but it's only ever existed as a design on paper and isn't likely to ever fly.
This news is confirming that Block 1B is probably also never going to fly. Instead Block 1 will launch the big two missions.
IMO it works well. SLS is a doomed rocket but this allows it to at least save face and do a couple things before being cancelled. Block 1B and Block 2 will never fly but Block 1 will get 3-4 launches in and call it a day.
