Just to clarify: 2.1 is extension, Silver is Rewrite?

If my assumption is correct then don't we want keep the 2.1 changes to
minimal with changes that only reflecting missed use cases from 2.0. If new
SCs coincide with 2.0 SCs they only strengthen them. 2.1 won't fix all gaps
caused by changes in technology.
Shouldn't Silver make those updates?
I'm just a little confused about things that seem like structural changes.
Wayne