Yes. One of two things happens when a publication stops publishing. Either they delete the publication or they leave it up but stop adding new material. If the owners of a publication delete it, any story you published in it will stay on Medium and it will just look like you self published it. If they leave the publication on Medium it will look like any other publication and your story will stay inside it, there just won’t be any new material added. You can always choose to remove your story from a publication and submit it to another one but most publications don’t accept old stories and if they do most publications list stories by original publication date (the default setting for Medium) so your old story gets buried.