There is a future quarterback plan at the Broncos' Dove Valley headquarters although John Elway would never dare draw it on paper. Wouldn't want any visible evidence for Peyton Manning to see. But if the laws of mortality hold the day will come when Manning now 37 no longer is the Broncos' starting quarterback. If it can happen in Indianapolis it can happen here. That day might be four years away. It might arrive after next season. It might be for a quarter and a half while Manning ices a twisted ankle during this soon-to-be-starting season. The future quarterback's name is Brock Osweiler. In the Broncos' 32-24 loss to the Arizona Cardinals in the fourth and final preseason game Thursday night at Sports Authority Field at Mile High Os- weiler played as though he's ready should coach John Fox call on him for the present. Osweiler's first three drives did not need to be cut up and spliced into a highlight reel. No edits needed. On his first drive which ended in a touchdown Osweiler drilled intermediate completions to Gerell Robinson and Jake O'Connell. On his second drive which resulted in a short Matt Prater field goal Osweiler gorgeously floated a 45-yard post-pattern completion to Robinson. On his third drive Osweiler demonstrated mobility running once for 11 yards another time for 10. He started with 7-of-7 passing finished the first half 7-of-11 for 108 yards and was rewarded by getting the second half off. It was easily Osweiler's most polished and productive effort since Elway the Broncos' boss of football operations selected him out of Arizona State in the second round of the 2012 draft.