I don't see any heroes being quirkless now. The bullets were already the last moments of a chapter I don't think Hori will make an other chapter with the erasing bullets as hype. Shiggy used 2 bullets : Bakugo destroyed one and an other hit Eraser. So maybe Shiggy has only one bullet left. I think he will keep it to make other bullets later when he will reign over Japan, during time skip etc.