It's training camp, all teams will have 3 or 4 QB's on the roster. They'll have multiple practice squads going at once, will need multiple QB's to run those squads. Now, come final cut day to the 53 man roster and they still have 4 QB's?
Personally I think Chip Kelly realized that neither Foles or Sanchez was going to cut it as the starter in his system (although this is puzzling as Foles was outstanding before he got hurt) and that Sanchez was the better choice for a backup (price being a factor). Everyone knows he wants Marcus Mariota, so is this whole Bradford trade/Tebow distraction just a smokescreen to a plan to move up somehow to the #2 draft spot? I hope so. I'd like to see Chip get what he wants and see how it works out. I'm not a fan of any one team so much as I am a fan of good, entertaining NFL football, so I'd be glad to see the Eagles get what they want and do well with the Chip Kelly thing. It'll make for fun football to watch.
The one thing that sticks in my mind though. If Kelly ends up with Bradford starting and Sanchez as backup, he has a lot less than he had last year (not to mention the other roster losses they just suffered). Bradford is older, not mobile, never was a runner, strictly a pocket passer. If he doesn't fit in with the system or takes another hit and goes down again they're probably looking at an 8-8 record, or worse.
These are horrible times and all sorts of horrible people are prospering, but we must never let this disturb our equanimity or deflect us from our sacred duty to annoy and hinder them at every turn.