We can absorb Knox' loss as a kick returner cause the new kickoff rules have pretty much taken KRs out of the equation.
His role as a field stretcher will be harder to replace. Either we'll have to keep using Hester on certain plays in that capacity, or we'll have to draft a burner or sign one in FA.
The past few years our offense has overemphasized speed at WRs at the expense of size... but you don't want to swing the pendulum totally in the other direction either. Even if we are going to a WCO-type scheme with Tice, someone's got to be able to keep those DB's honest or else you can't get things done over the middle and your ground game gets plugged up too.