Metering flow will 1000% increase attrition. Anyone who still hasn't had their apps out will get them out overnight. Envoy will lose half of all CAs in 3 months, those cute FO leaving posts will be replaced by high time CAs from 2016 to 2017 hires. New hire's number will also drop by half.
I personally want to see it happen. Envoy will begin shrinking back to a 1500 pilot group.
In contrast. Doubling flow to 40 and adding a 24 month CA flow lock might kick the can down a little longer.