So,
1. Weather conducive to icing
2. Wing very sensitive to contamination
3. Previous accidents which are similar phenomenologically (wing drop shortly after TO)
If the AC was not deiced before takeoff, there has to be a suspicion that this is at least partly due to icing.
The problem with determining wing icing to be a (the) cause is that direct physical evidence is absent. So, given that the phenomenology as reported by some is consistent with asymmetric lift, icing would be an explanation whose strength derives directly from the weakness of evidence for alternative explanations. It is, logically, an explanation by default, and therefore subject to all the difficulties of explaining by default, such as the effectiveness of the search for other explanations. If something else physical is amongst the causes, then finding evidence for that is dependent on how carefully the burnt-out wreckage is investigated.
Kazahkstan is a participant in the Interstate Aviation Committee, which includes the Russian Federation, so I presume the MAK will be investigating.
PBL