I'd be willing to bet my house that this is not a case of continuing the approach below minimums without visual reference. If the pilots hit minimums (or lost visual contact after minimums) there is absolutely no doubt in my mind that a go-around would have been initiated.
So, yes, a improper vertical path is possible but I'm sure that it would not have been followed blindly to impact. It may have left the pilots in a unexpected position upon breaking out and then a mixture of optical illusion (black hole effect, snow streaming by the landing lights, crab angle, insufficient approach lighting, etc), turbulence and possible windshear may have led to the aircraft coming in too low. Personally, I think unreported severe windshear will be a primary cause.
I will be very interested to see if the PAPI's were working properly (or at all) as the final visual segment would have been significantly more difficult without them.
And, while low in probability, a loss of power or unresponsive throttle fault (ala British Airways) also could have occurred.