On the heels of Jim Boeheim recently commenting on lost rivalries (specifically, Boeheim said people didn't care about rivalries anymore), Athlon came up with a list of lost rivalries killed by conference realignment. Pitt showed up in two of the ten slots, with their rivalries against West Virginia and Penn State.
We all know that the Backyard Brawl was a direct casualty of Pitt and West Virginia leaving the Big East, but when it comes to Pitt and Penn State, Athlon's statement below simply isn't true:
When Penn State joined the Big Ten, it all but ended the series.
The rivalry among those two teams was played several more times after Penn State joined the Big Ten. I know, because I suffered through many of those games as a student. I'm not going to turn this into a 'Pitt and Penn State should still be playing' discussion - that's not the point. But the rivalry could have been continued even with Penn State's move. The two teams going their separate ways didn't help things, but it certainly isn't the only reason they stopped playing.
But back to Boeheim's point. I have a hard time buying into rivalries not mattering anymore. People care about rivalries and even with expansion and realignment and that's evidenced by the constant insistence by fans that Pitt renew rivalries with the Mountaineers and Nittany Lions. Plus, if two teams are committed to playing against each other, series can continue. And also to Boeheim's point, new rivalries will develop in the midst of realignment. Pitt developed a bit of a basketball rivalry with UConn over the years. For a few years, the Panthers had a small rivalry with Cincinnati in football.
Another example of this is Pitt-Virginia Tech. The two teams had a bit of a rivalry while they were in the Big East partially because Pitt had some success against the Hokies. That rivalry ended when Virginia Tech moved to the ACC, but with the Panthers joining them next season, that's another rivalry that could pick up in the future.
The bottom line is that even with constant shifting in college athletics, rivalries aren't going anywhere. Some may disappear, but some will remain and new ones will develop over time.