Ah well, although we are probably only hours away from FDR results of procedure flown, pitch, roll, yaw,.RPM, RadAlt, CVR transcript etc, I might as well join the speculation.
Are we certain there are no gear marks before the start of the pictures? Why would the gear be up? I would deduce that the 'furrows' seen at the start are dug by engine exhaust. Once the tail separated (presumably survivor seated here and ejected?) the pitch of full power would rapidly raise the nose, followed by a rapid nose down following a stall and an extremely hard final impact collapsing the forward section. How's that? Fits with the Alitalia visual too.