3. The Story
This is likely the most important issue here. The story of GTA is always "guy moves into town, rises up, takes it over." GTA IV had a great story driven by character rather than plot, but I hope GTA V brings something a bit fresher and more creative to the table. The possibility of a protagonist having kids is a great one, as it is something that could give them a personal motivation and a reason to stop killing and stealing. That sort of complexity is something we haven't really seen before, and it's certainly something that might lead to a deeper and more engaging experience.
How to fix it? Try to avoid using stereotypical characters, plot points and themes. Russians and Mafia mobsters? No, no, it's just not necessary to be so one dimensional. Cult groups and family stories? Yes, please. Rockstar needs to really give us something different to make the plot feel worthwhile rather than a reason for the game to progress, and while it wasn't a problem in GTA IV, it is possible that GTA V could suffer the same fate as some other more limited games of this year. And that would be bad.