The situation is genuinely concerning. Lower population estimates combined with poor individual health means the species faces real pressure. Disease (chlamydia is a major one), habitat loss from deforestation and development, drought stress, and bushfire damage have all hammered them hard. Victoria's situation is particularly bad, but the broader trend across Australia isn't great either. You're right to take it seriously.
That said, "extinction" isn't the same as "critically endangered," and there's a difference between local collapse and species-wide collapse. Koalas still exist across multiple states, and there are active conservation efforts - habitat protection programs, disease research, breeding initiatives in some areas. It won't fix itself without intervention, but it's not a "koalas will be gone in a decade" scenario either. The realistic picture is: they're in trouble and need real action, but they're not already past the point of no return. Climate and land-use policy matter a lot more than most people realize.