Righteous Fire was certainly fun, and a more or less worthy expansion (it could have used a new ship, though). Plus, its final mission was a real stand-out, because for the first and sadly only time ever in the history of Wing Commander, you actually were forced to navigate by the sky. That's something they should have done on a few more occasions.
...But did it really breathe new life into the universe? I would argue that no, it failed in this regard. That's not a criticism of RF, though. It was mission impossible to begin with. Privateer just didn't offer enough to allow long-lasting play without dullness setting in. The universe was sadly repetitive - once you've seen one mining base, you've seen them all. The need or money certainly kept you taking on those generic missions for quite a long time, but eventually you maxed out your ship, and there simply wasn't any threat to you any more. When RF came along, it wasn't new life so much as artificial life - ok, there's a few additional parts to buy, I guess I'll play long enough to buy them. It felt more like something you did out of obligation than out of any genuine need. Buying them, of course, just amplified that feeling that hey, this universe really has nothing to offer any more.
Don't get me wrong. Privateer was mostly a great game. There really wasn't much else they could have done with it (well, ok, maybe having a few more capships, including carriers that would be well-nigh impossible even when maxed out). But the game was ultimately constrained by its limitations. Even so, it still felt infinitely superior (in some aspects) to both Privateer 2 and Freelancer, so hey - it did more than well enough for itself
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