Wait, sorry, reading all of the words now.  Sold for a gain, the QBI loss would probably offset any ordinary income from the sale of the business (depreciation recapture, sales of A/R or inventory, etc.)  It can't offset any capital gain though, by statute.  Sold at a loss, yeah, I think it just carries forward until (cross your fingers) this whole nonsense expires in 2025.

Somehow we went from a 2-page tax form to a "postcard" and now to an 8-page tax form.  You know, simplification.