It's not really particularly worrisome. Imgur makes it easy to download your entire library with one click, download any favorited album with one click each, all in zip format. So cutting ties with Imgur is simple.
That said, all this is really doing is bringing the "hidden" side of imgur in line with the community policies of the "public" social media side. Not much will change for the imgur "community," and redditors using it as 3rd party image hosting will just migrate to the next one, same as happened with tinypic, photobucket, etc etc etc.
Really, as I've often said, Imgur has been circling the drain for years, ever since they started courting advertiser dollars and trying to pass themselves off as their own social media platform instead of a simple image hosting solution.
On a semi-related note, guess who's got two thumbs and got banned from Imgur yesterday for rapid fire NSFW posts in a comment thread?
Interestingly enough, being "banned" from imgur doesn't stop me from uploading/downloading/favoriting/upvoting/downvoting/embedding media. It only cuts off my ability to post/reply in comments and send/read private chat. Oh, and editing my profile's bio.