"You can continue to use an EHIC or get a provisional replacement certificate (PRC) if you need treatment and do not have a card.
If you apply for a card now, you'll get a new UK Global Health Insurance Card (GHIC) instead of an EHIC. These pages and the application portal will still refer to EHIC until 4 January 2021.
You do not need to apply for a GHIC if you already have an EHIC. Your EHIC remains valid in the EU until it expires."
(Link to NHS site in my post yesterday)