The most realistic sign of protocol maturity may be how boring the updates now look.
After major simulations, institutions are increasingly issuing narrow revisions to logging order, disclosure thresholds, witness rights, freeze authority, and inter-board escalation rather than announcing grand new doctrine. That pattern suggests the governance layer has moved from speculative design into iterative maintenance.
In practice, that is what stability usually looks like. Systems stop changing through manifestos and start changing through careful correction after every serious rehearsal.