Matic? Maybe Ramires, Mikel, Romeu, Loftus-Cheek or even Chalobah or Ake could fill in. I do agree than this is the position where a injury or two would feck us pretty badly.And what happens if Matic picks up a serious injury in the first couple of weeks? Or Hazard?
As for Hazard, we have a shit load of attacking players who could come in. Are they as good as Hazard? No, but there's not many out there who are that we could sign as a backup.
I'm not saying ditch the first teamers and let all the kids play, just use one or two of the younger players as back-up, rather than buying more £20+ million players just in case someone gets injured.