We know almost nothing. So little data has been made public that making any assumptions and conclusions is quite premature, if not simply stupid. Nothing can be said for sure without going through the entire CVR transcript, while at the same time looking at the FDR data.
I have an unrelated question. One of the error messages transmitted by the aircraft was
NAV TCAS FAULT (2 h 10)
Meaning: This message indicates that the TCAS is inoperative.
Is there any explanation why TCAS would fail? It seems completely unrelated to airspeed...