...Oh, wait. We _can_ do that now.
Introducing Text iQ-Powered Survey Flows. As respondents provide open feedback on your survey, Qualtrics can assess the sentiment of the response, topics used in the response, and the sentiment of those particular topics. Once these calculations are made, you can use branch logic to send respondents to different paths in the survey depending on the sentiment or topics present in their response.
!

!

This feature was just released, and is available to everyone with Text iQ.
(PS - This feature uses a lot of the same functionality as Text iQ, so make sure you brush up on sentiments, topics, and especially building queries.)