Creation of an "AMAZON.ExtendedHoldIntent" type intent.

To the user, the device clearly indicates to be in a waiting state by graying out or blanking the screen.
A mauve to white to mauve triangle wave flashes on the hardware LED(s) as the indicator.
"(wake work +), I'm back / okay / continue etc." re-triggers the previous speech directive and prompt etc.
AWS modifies the Lambda’s context.
The Alexa Skill triggers the lambda with previous attributes and is not a new session.
Amazon decides how best to handle the Lambda compute use time increase, or which maximums are allowable.

Creation of a "Audio Recorder" Interface:

"Alexa call 555-1212" does part of this already.
The Echo firmware needs to be updated.

The directive to the hardware contains some new additional fields.

The directive is received containing an S3 target and credentials.
The creation of an "AMAZON.RequestAudioRecordBeginIntent" intent could serve to satisfy as proof of user intent by the utterance keyword(s) and require mandatory re-confirmation.
The echo initiates the opening of the microphone with an indicator to the user, and begins storing the audio on the hardware. The wake word engine triggers a truncating of the audio, starting the from EOF, backwards to the wake word + "stop".
A green to white to green triangle wave flashes on the hardware LED(s) as the indicator.
The permissions settings include specific consent to allow captured audio for that skill.
AWS modifies the Lambda’s context.
The Alexa event endpoint receives its payload, but its behavior is limited to ‘write’ to the target storage endpoint specified in the new directive type. The Alexa Skill triggers the lambda with previous attributes and is not a new session.