@mdhughes I'm not deep in Scheme lore and haven't followed the standardization process. Here's my take as a mere lazy user of Racket and R5RS+:
As I understand it, R5RS was most importantly an R4RS with a codified macro mechanism. R7RS-small was most importantly R5RS with a codified library mechanism.
If there is ever an R8RS I hope it mostly just codifies the de facto R7RS-small+ with unicode and whatever else "everyone" had to solve based on real-world concerns and doesn't try to advance the language beyond that.