Let me first say that I don't think the Corsair presence in O-49 should just be written out of Disco and all memories of it swept under the rug. On the contrary, I think it opens up lots of RP opportunities if played out smartly. And besides, Corsairs are like a bug infestation: once they're in, it's awfully hard to get them out:P(I'm only kidding, right guys? Guys?) The Zoners would have a hell of a time just kicking out a group as powerful as the Corsairs.
The problem right now is that O-49 is like candyland for the Corsairs: there's absolutely no one there to give them the slightest resistance (save the rare BH patrol). I'm fine with Corsairs pirating there, but currently it's like a Sair playground.
Speaking from a Molly perspective, I've chased traders/Corsairs/whoever into O-49 on a few rare occasions, only to be greeted by Titan swarms that rival anything in Gamma. Like what's been proposed, eliminate Corsair patrols in the niobium field - maybe even the entire western half of O-49 - and throw in some Molly or Zoner patrols. After all, it's a risky diplomatic proposition for the Zoners to allow Corsairs that close to Dublin and another entrance into Bretonia: the Mollys would obviously be pissed, but so would the Bretonian House in general as that opens a potential second front into their territory.