GTA4.Net noticed this "ad" in the Episodes from Liberty City instruction manual that, reading between the lines (or around the torn out part, anyway) seems to tease where the series is headed next. And maybe when.
The ad, apparently for a fake movie, declares "Liberty City, It's Over!" implying, naturally, that we're all done here. "Next stop," it says, and that portion appears to be torn out, except for the word "Seagull." I think it looks like the name of a hotel, but who knows.
To the left of that is "Opens March Everywhere," and your guess is as good as mine as to what that means. But Rockstar knows what it's doing here, it's getting people to talk, and we've taken the bait.
(A picture of the entire "ad" is at the link below.)