If the current owner agrees, they can
- anonymize all users (since the data will not be under their control any more)
- remove all references to their brand or trademark(s)
- provide a backup to someone they trust with it
and that person(s) can
- get a domain name
- get hosting (self hosted, or with communiteq.com or with discourse.org)
- restore the backup
- enjoy
If the current owner does not agree then any attempt to archive this forum is probably illegal in some way.