Some potential if you find the right end user/entity.
Despite the exact term getting 0 searches, the term IPv6 gets 201,000 exact global searches, 27,100 local. So there is type in traffic potential for a buyer. Definitely one of those domains which depends on a very specific buyer willing to develop a site.
If someone really wants a site on IPv6, I think you could pull in low $xxx. If renewal were to come up and no bites or bids I would not renew.
Best of luck with it!