I do think we have to look to replace him very soon. He is coming up on free agency in 2014, the same time as JPP , Linval Joseph, Hakeem NIcks ,possibly Chris Snee(voidable year) among others. The Giants simply will not be able to resign everyone.
As much as I love Tuck, he has been on decline and they will have to let some of the impressive names coming to free agency go.
If we draft a Werner, or Carradine, or some other DE, they can develop for a year, contribute a bit and step in next for a primary role, exactly how we did it with JPP.