Information from: “Aché Documentation Project (ADOP)” . Jost Gippert and Sebastian Drude (2013)
60 percent certain, based on the evidence available
MORE ON VITALITY
"Intergenerational transmission is interrupted, as only older generations speak Aché fluently and in most speech domains. The younger generations have switched to the two national languages in Paraguay: (non-indigenous) Guarani and Paraguayan Spanish."