I know that questions about incidents under investigation are generally off topic; see e.g. Should we comment/speculate on incidents being investigated? and Frequent questions following air incidents.
However, what about incidents where an official investigation report is available, but that report is broadly inconclusive as to the fate of the aircraft or the cause of the incident? For example, consider Malaysia Airlines MH370. On Oct 3 2017, the final Australian Transport Safety Bureau report (direct PDF link) was released. Quoting from the executive summary at the previously linked ATSB page,
Despite the extraordinary efforts of hundreds of people involved in the search from around the world, the aircraft has not been located.
Regardless of the cause of the loss of MH370, [...]
The intention of this report is to document the search for MH370, in particular, the underwater search including; where the search was conducted (and why), how the search was conducted, the results of the search and the current analysis which defines an area where any future underwater search should be conducted. The report also includes a safety analysis which is focused on the search rather than on discussing the range of factors which may have led to the loss of the aircraft.
While I haven't read the report myself, it's pretty clear already from the executive summary from the ATSB that the ultimate fate of the aircraft in question during the last several hours of the flight remains unknown.
In such cases, are questions about such flights on topic because an official investigation report is available from which material can be quoted, or off topic for the same reasons why questions about incidents under investigation are off topic? Where should the line be drawn?
(This question was prompted by the question What happened to flight MH370, which may be at risk of being automatically deleted as low quality, and discussion in the comments to that question.)