Of course, he can be replaced. Most players can. Murray would've been a known in Dallas though. Now you have to hope they find a viable replacement. We both know McFadden isn't it.
You can't just throw McFadden, Dunbar, Randle, and a rook out there and expect to completely replace Murray.
I don't necessarily think Murray would have a been a known, it would be hard to project his production in 2015 considering how many carries he had to withstand last year. History doesn't look favourably on backs coming off 400+ touches. So even if Murray came back to Dallas, he probably doesn't match the production he had in 2014.
Now trying to match Murray's 2014 production, I think the Cowboys come close. They still have Romo and Dez to counter 8-man fronts, they still have the personnel to go heavy or jumbo and be effective. They just have to find a back or a committee of backs that can match Murray's talents.
Murray's skillset isn't great compared to backs like Le'veon Bell. But his skillset was a good marriage for the what the Cowboys liked to do. He is a decisive, down-hill, one cut type of back. I don't think it will be difficult to replace his skillset , he isn't a particularly gifted runner like Adrian Peterson, he can't create for himself, he needs the system in my opinion.
McFadden was never seen as a replacement for Murray by the team, he was seen as a back up with explosive ability. The team signed its low-risk FA with him, they will look to the draft, UDFAs, street FAs, bring em in to TC and see what comes out . I don't know who will emerge, but I don't think it will be hard to replace Murray, because his skill set isn't hard to replace and the other components of the offense are still there.
Want to throw this out to the rest of the thread for discussion, and I would love to be corrected, am I wrong to suggest Murray's skillset isn't difficult to replace, considering the prospects that are coming out of the draft?