"Patients with Long COVID report prolonged, multisystem involvement and significant disability. By seven months, many patients have not yet recovered (mainly from systemic and neurological/cognitive symptoms), have not returned to previous levels of work, and continue to experience significant symptom burden."
https://www.thelancet.com/journals/eclinm/article/PIIS2589-5...
Frankly we don't really know how bad the long term effects will be for even those with "mild" illness.