I think they absolutely would keep on winning...especially against the USU's, UCF's and UNR's of the world. I don't think it's an unreasonable expectation for BYU to beat these run of the mill MWC type teams without a few starters on the field.
Besides, BYU's defense was exposed long before the injury bug hit. Our defense was on the ropes against Virginia and Houston. Our ineptitude on defense is a scheme thing as much as it is an execution/lack of experience thing.