had an opportunity to cash in on a millenium doomsday/y2k angle

I can't conceive of a Y2K-themed plot that isn't silly, like "an evil nerd group wants to bring [first world country] to its knees, so it poses as programmers hired to 'fix' the Y2K bug, but instead they disable.... stuff, and then the entire country is at the mercy of the evil nerd army and its leader, a crude parody of Bill Gates."

Even if the plot isn't specifically about Y2K, what would it be about? Terrorism? TWINE already involves a terrorist plotting to blow stuff up, albeit not on a global scale.

How exactly would a millenium doomsday/Y2K angle for a James Bond movie necessarily be an "opportunity"? The James Bond franchise had already had movies dealing with computers so such an angle wouldn't really be new. And it wouldn't necessarily be a better plot in any way than what this movie actually had so they wouldn't necessarily "cash in" any more than they actually did. It should be noted that The World Is Not Enough made more money than both of the previous 2 James Bond movies.

To be honest, and this feels weird to say, I think that'd be too silly. I know it's Bond and silliness is part of the franchise, but there is a certain type of silliness that works with Bond, and Y2K wouldn't be it. It'd feel too "techy," if that makes sense. Plus, it'd date the film horribly since Y2K was such a specific moment in time. Even the Cold War Bonds would age better than a Y2K angle.