Medical incapasitation
This approach flown by an experienced pilot was so bad in terms of airspeed and touchdown point that I can only reach the conclusion that he was suffering from a serious incapasitation.
As the aircraft seems to have been functioning well at the time of impact and the fire was intense it is likely that mechanical problems and fuel shortage are unlikely to be issues.
With the Germanwings case in mind suicide would seem an unlikely scenario simply because the approach was so badly flown as not to guarantee the intended outcome of this purely hypothetical scenario.
The postmortem on the pilot is likely to hold the key to this accident but all the indications tend to point to the medical incapasitation of the pilot at a critical time in the flight, however the medical evidence could well have been consumed in the fire.
It may be that the AAIB are not able to come to a firm conclusion to the cause of this tragic accident but the identity of the passengers is likely to be fuel for all sorts of conspiracy theory's that will run for years.