This seems fairly straightforward to me (not solved, but the mysteries remaining seem pretty linear).
Aircraft on short final slows to a speed that cannot support flight. It may be very hard to "stall" a 737, but at a slow enough speed it (and anything down to the size of a Warrior) will develop a high sink rate ("fall out of the sky") even if the AOA and airflow are not in a technical stall.
Slow forward speed is consistently supported by short debris trail, witness accounts, "flat" or tail-low impact posture.
Weather reported (stable, stratus layer, no vertical development, no CNB) is not consistent with a wind-shear event (but a severe wind shear would produce similar results and appearances - at the right time of year).
Wake turbulence usually results in roll effects - this seems to be a wings-level pitch incident.
So - why was it slow?
Low thrust seems to head the line of suspects. (Witness reports of relative silence of plane, from inside and outside the hull, engine state as visible SO FAR(!!))
> Birds in engines? Not impossible (Cactus 1549, Ryanair/Ciampino).
> Fuel contamination or blockage? Could be (BA 777).
> Failure to set thrust correctly? Not unheard of. (Continental/Colgan 3407 - although still a big big MAYBE in that case).
> Fuel exhaustion? I have doubts myself - but it has happened more times than I would have expected in jetliners.
That's where the FDR and CVR come in handy. Plus DNA checks of the engines. Etc. etc. The investigation.
Now - evidence could still appear that contradicts me. Signs the engines were producing high thrust at the time of impact (physical state plus data records). Something like the magic air tank from the Qantas/Manila event - that introduces a whole new factor. We've been "surprised" by the obvious quite a few times in just the past year.
If I were on the investigation team, I'd be looking for facts. And just as happy to find ones that proved me - wrong - as proved me right.