Since the time of the original post, I've been reading a lot of the feedback posted here as well as discussed privately. I appreciate the concerns raised, and some of the ideas presented were intended to be controversial. Suffice to say, current plans and in-progress changes do look quite a bit different from the posted proposal.
One of the inhibiting factors when it comes to removing/deleting systems, even the boring ones, is that it can create unintended shortcuts that are challenging to balance. In particular, the concept for Sigma-21 as presented is problematic, so we're going back to the drawing board on that.
In the coming weeks I aim to have some per-region plans drafted and posted for discussion. I will leave this thread unlocked for now.