Well they have always got a backup plan if all else fails, a whole back catalogue of known to be some of the best games made to bring to the XBLA. It's just up to them if they want to live off past glories because once that runs out they're kinda screwed and might lose more credibility as a developer for just being a shadow of their former self and it'd be quite sad if the only way they could make money is by their old games.
Saying that I'd still pay anything for Perfect Dark done in the way Goldeneye XBLA was made, really really want that game
And they've got a whole engine made for it already so it shouldn't be too difficult. Saying that the fact Goldeneye could never be released doesn't help in any of this actually, considering how much time they must have spent making that game for it to never be released.