There’s so much speculation about Texas quarterback Arch Manning’s future, in the media and even within his own family, that it can be hard for even him to keep upAUSTIN, Texas — There’s so much speculation about Texas quarterback Arch Manning’s future, in the media and even within his own family, that it can be hard for him to keep up.On Tuesday, Manning insisted he’s not plotting out how long he’ll stay at Texas or when he’ll enter the NFL draft, despite his grandfather’s recent prediction to Texas Monthly magazine that he’ll be with the Longhorns through the 2026 season.“I don’t know where he got that from,” Arch Manning said in his first meeting with reporters since SEC media days in mid-July. “He texted me to apologize about that. I’m really just taking it day by day right now.”Arch Manning has been careful while talking about his future as he leads the No. 1 Longhorns as the full-time starter after playing behind Quinn Ewers the past two seasons. Manning enters this season as the early favorite for the Heisman Trophy, has endorsement deals worth millions and comes from the most famous quarterbacking family in football. Grandfather Archie played in the NFL and uncles Peyton and Eli combined for four Super Bowl victories.Add that together and Arch Manning is shouldering the biggest spotlight of any player in the country. Texas opens the season Aug. 30 at No. 3 Ohio State after losing to the Buckeyes in the national playoff semifi …