Based on prior NCL history-looks promising. Using the way back time machine, NCL posted this response in their FAQs from April 2021-August 2021:
Yes, if a guest has an active reservation as of April 5, 2021 for a cruise with a vaccination requirement (currently all sailings through October 31, 2021), that the guest is unable to comply with; guest will be permitted to apply the full value of all amounts paid to a new future cruise credit or, at their discretion, be provided a cash refund in an amount equal to their original cash payment by visiting https://www.ncl.com/case-submission. For reservations that were made on or after April 6, 2021 the refund amount will be subject to Norwegian’s cancelation fee policy communicated to our guests at time of booking and can be found on our website https://www.ncl.com/about/cancellation-fee-schedule