PubMed 2 will become default around May 18

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.