SmugMug acquired Flickr on 19th April, and the official date for the handover is on the horizon. So, it would be wise to back up all your Flickr images, and probably not upload anything new. I have heard of Flickr account holders uploading images only for them to disappear for no apparent reason. Could it be that servers are already being turned off or reconfigured?
When is it going to happen?
Deadline day is Friday 25th May 2018. On that day everything will be transferred to SmugMug. The Flickr blog says that users should not be affected in any way. Including the fact that image URLs will remain the same. While I'm sure they have redundancies in place, data loss and file corruption are possible. Not to mention the possibility of security breaches taking place. In addition, while SmugMug promises not to change anything, it is mostly a paid for service so don't be surprised if you start receiving subscription advertising. There is no reason I can see why SmugMug would buy out Flickr unless it expects to make money. It just doesn't make sense.
So what should you do?
First of all, it's vital to back up your Flickr data now. Then go to the SmugMug website and check out what terms they offer https://www.smugmug.com/about/terms-flickr. If you are not entirely satisfied, the onus is on you to delete your Flickr account before deadline day. By doing nothing, you agree to SmugMug's terms and your account will fall under their jurisdiction. According to Flickr's blog, nothing will change and all users will live happily ever after. Call me cynical, but things never remain the same in an acquisition. In time, goal posts get moved and what you think you've signed up to isn't what it was.
I'm in two minds what to do about my account. I don't use it as a professional photographer and I also have an account with 500px which provides a similar service. However, my account is important for my blog and engaging with other photographers. I'd be interested to hear what you think, in the meantime here's some advice on how to save your files and delete your account.
How to download your files
On your Flickr page click "You" -> Organize
In Batch orgazine click "Select all" and drag images into the main panel
Select Add to album -> "New Album"
Give album a name -> "Save"
Leave the page and return to your Photostream. Go to "You" -> Albums and then click on the new album you have just created.
Once the album page opens up, click on download icon -> Create zip file. You will then receive a Flickr Mail notification when the file is ready to be downloaded.
Deleting your Flickr account
If you decide that you want to cancel your account, you should tell your followers that you intend to do so. After downloading all your image, you can just upload one that informs them of your intention, and in the description put some links to where else they can engage with you, such as Instagram, Facebook or your website.
Deleting your account is quick and permanent.
Simply click on Settings -> Personal Info -> delete your Flickr account.