I've got to say, I've been so preoccupied with Pitt's move to the ACC, potential games against Penn State, and talk about getting the Backyard Brawl going (or not), that I've not given much thought to the idea of a conference rival for the Panthers.
ESPN looked at it recently and offered some options including Virginia Tech, Boston College, Miami, or Georgia Tech. I don't get the Yellow Jackets - at all. Miami and BC could be options, but Virginia Tech is the obvious one simply because Pitt has given them so much trouble over the years.
Frankly, I'm not sure how Syracuse isn't given much more consideration (and to be honest, they weren't even mentioned as a possibility, which is odd). ESPN looked at rivals for Pitt and Syracuse, but in reality, Syracuse could be a good one for Pitt. The Panthers have dominated them in recent years, but there's not only the Big East history, but the schools are also a bit closer than some other opponents.
I don't know - the whole Pitt-Syracuse thing never really took off in football since Pitt has always had West Virginia (and previously, Penn State). But with those games gone for the near future, that could change a little. The problem is that rivalries aren't built overnight and Pitt will resume a series with Penn State in a few years. But if we're talking in-conference rivals, the Orange could a possibility.
And also, looking ahead, Louisville could turn into a nice rivalry for the Panthers as well. Especially because the Cardinals are an upcoming program.
Virginia Tech's probably my pick for now, but Pitt and Syracuse/Louisville could have some interesting games as well.