Announcement from NLM: New PubMed to Replace Legacy PubMed in Mid-May
The date will be May 18.
From the FAQ: https://support.nlm.nih. gov/knowledgebase/article/KA- 05275/en-us It said: “Links to the legacy site will be redirected to the new site. The redirects will be persistent, so old links will not “break" — they will go to the new site once it becomes the default."
The old site will still be available, but will go away in a few months. Users should move to PubMed2 sooner rather than later. There are more information in the FAQ.