There's no doubt the 49ers will extend the contract of quarterback Colin Kaepernick, whose initial rookie deal will expire after the 2014 season.But after the roster moves the Niners made this past week – in the draft and via trade – the long-term future of wide receiver Michael Crabtree and left guard Mike Iupati would seem a bit cloudier. Both players' contracts also will run out after this coming season.In a perfect NFL world where salary caps don't exist, San Francisco certainly would keep both players. Crabtree has been the 49ers' best and most consistent wide receiver and the favorite target of Kaepernick. And Iupati has been an All-Pro, a strong, devastating run blocker who's been a key member of what has been one of the league's best offensive lines.But during the three-day draft last week, the 49ers traded for veteran wide receiver Stevie Johnson of the Buffalo Bills and selected speedy Bruce Ellington in the fourth round. Those two, combined with Anquan Boldin, Quinton Patton and Brandon Lloyd, give the team a deep and talented receiving corps. It's possible that if Johnson and Ellington produce in 2014 and develop a chemistry with Kaepernick that the 49ers...