Last i remember there were problems with Panther Aselsan were designing new version of it.Considering like you said we dont ever see their usage its safe to assume all of them probably pulled out of service.
Or wait for BMC-Rheinmetal factory to get finished first so when tender eventually given to BMC people won't be able point the fact BMC dont even have necessary facilities(nor enginners) to mass produce Altay.Two birds with one stone really and who gives a shit about adding another year to...