A 25-year-old woman presents with generalized petechiae and ecchymoses for 2 months, and prolonged menstrual bleeding lasting 10 days. Gynecological examination is unremarkable. Laboratory tests: Hb 90g/L (anemia), WBC 6.5×10<sup>9</sup>/L, PLT 32×10<sup>9</sup>/L (thrombocytopenia). Bone marrow shows active proliferation with 218 megakaryocytes per slide, predominantly granular type. After corticosteroid treatment, the most likely prognosis is: