I wouldn't mind seeing some of these:
- Bounty Hunting co-op missions
- Snowboarding races on mount Chiliad etc. (with an option to modify your snowboard with decals/patterns/colors etc) and a place to display it inside your apartment or garage's somewhere for others to view.
- Bowling // pool table games to return.
- horse races / horse race betting bookies (races which can be seen at the local track or also be viewed by you/other players live from the comfort your in-game apartments tv ).
- scuba diving treasure hunting missions // co-op
- las venturas,san fierro,vice city added in the future as locations to explore,do missions/heists and generally cause havoc in
- The Ex-Presidents masks that were featured in point break movie (Ronald Reagan, Richard Nixion, Lyndon B. Johnson , and Jimmy Carter) included in-game and usable on heists.
- Breaking Bad tv series Heisenberg mask (though i'm guessing this ones asking a lot since it probably falls under likeness rights).