They could always bring someone in if they feel the need to. In fact, I see the Bills going all in this season. I believe we could see another veteran WR and CB brought in.
I wouldn't be shocked to see Davis explode this season (would any of us be shocked?) and add Diggs, Knox, Shakir, Hodgins, Crowder, Cook and Motor in...to me it appears the Bills offense if loaded for bear.
I have no worries about the offense with the exception of significant injuries happening.