Marcus Stroman might have already thrown his last pitch of the season for the Chicago Cubs. Or the right-hander could throw important innings down the stretch as they vie for a postseason spot. The Cubs aren’t ruling anything out amid the range of outcomes and uncertainty surrounding the rarity of a new injury Stroman sustained earlier this week. The Cubs announced Wednesday that Stroman suffered a right rib cartilage fracture and will remain on the 15-day injured list, a move that originally was prompted because of right hip inflammation. There are so many unknowns about his short- and long-term Cubs future, whose player opt-out appeared at the midpoint of the season. President of baseball operations Jed Hoyer did not want to try to estimate when — or if — Stroman, 32, would be back on the mound for the Cubs this season. “I mean, I have no idea, that’s the honest truth,” Hoyer said Wednesday before the Cubs’ dramatic walk-off 4-3 win over the White Sox.