[2] Some poorly known extinct languages, such as Gutian and Cacán, are simply unclassifiable, and it is unlikely the situation will ever change.
An 'unclassified' language therefore is one which may still turn out to belong to an established family once better data is available or more thorough comparative research is done.
Extinct unclassified languages for which little evidence has been preserved are likely to remain in limbo indefinitely, unless lost documents or a surviving speaking population are discovered.
The obvious similarities are therefore now thought to be due to borrowings from Maba, which is the socially dominant language in the area.
Mimi might therefore be a language isolate, or perhaps a member of some other family related to Maban in the proposed but as yet undemonstrated Nilo-Saharan phylum.