This update means there'll be a new answer to questions, with the speaker now fobbing you off by saying it'll notify you should it ever work out the answer. The common response: "I'll have to get back to you on that". From that point on, Alexa will remember whenever she's unable to answer a question, and let users know when she learns the answer.
Now, Alexa's learned the same trick.
Now if you turn on Answer Update, it'll reply with "If you ask me a question and I don't know the answer but I find out later, I'll notify you".
It doesn't appear that the feature is fully up and running yet, though.
"Sorry, I'm not sure", she said, with no promise of providing an answer later once her database of local businesses expands. This could be a voice notification from Alexa itself, but since Alexa nearly never speaks to users unprompted, it's more likely to be a smartphone notification from the Alexa app. The notification will come on the device if you've enabled the feature, according to TechCrunch.
"Once Answer Updates is turned on, each time you ask Alexa a factual/informational question and she doesn't know the answer, she will go find it and send you a notification on the Echo device when she has it", Amazon explained. Hopefully, this kink will be worked out in the coming weeks, as Amazon continues testing the feature.