I agree, it's mind-blowing that ownership of surveys in CV hasn't been addressed in the two years it's been around. Again, there might be a way to accomplish this, though I have yet to come across it. Might be a good idea to submit a support request to Microsoft to see if they can assist.
Another idea going forward since you have people coming and going would be to establish a default user to administer/create the surveys and then grant/remove access to end-users as needed. It doesn't need to be an actual person, rather just a licensed user.
If Microsoft can't assist and no other option seems ideal, try keeping the surveys and data under the currently licensed user. Strip the contact information from the current user in the admin settings, change the password, and change the email address from "leavinguser@your-org" to "surveys@your-org" or something else. That way the user license technically stays active keeping all of your survey data even though the leaving user is no longer associated with that license anymore.
Just a thought.
Best,
Chris
