Hi Brendontroy,
It might depend on how you are having participants take the survey (ie. Anonymous links or Personal links)
A static list is probably easy to update if you are just using anonymous link, as it will be updated, almost immediately (best if you turn of save and continue in survey options) and since this is a text-entry question, the changes that you make to the static list will not affect data that you already collected, even if you completely change the list (unlike multiple choice questions and many other question types)
However, if you do wish to make the list more "dynamic" you could reference another survey's data as the source by having the survey open to multiple responses that you can add new responses to.
(ie. Have a one question survey set up as the supplemental data source and have the autocomplete question reference this Supplemental Data Survey. Also, you probably want to "import" the initial answer choices as responses into this survey. For future updates, you can either A.) Import responses as an excel or B.) Take the survey and create a new response, which will add the answer choice to the list. [great if you want to allow multiple people to add to the autocomplete list] )
Since this is a relatively new feature, you'll probably have some trouble getting assistance, but hopefully, I was able to provide a least a direction for you to head in.