Not sure if I care if it's done for single player or an online mode, but I really hope they do something a la GTA 5 Online's businesses, properties, safehouses, etc. not because I like shamelessly deliberate RMT whaling, but I'd love a reason to free roam, grind, hunt, do randomly generated missions, etc for months and months -- not just weeks as is the standard SP norm. i'd much prefer it in SP but i'll accept either method if it gives me a fur trapping business or gold mine to supply/make deliveries from while I'm patrolling desert plains and snowy mountain forests to collect on randomly generated bounties or something... just give me a reason to roam those gorgeous mountains for much of next year hhhh
It was a good game, had a lot of improvements over IV but also some weird downgrades I would say, compared to IV but also MP3 and RDR. I didn't like how fast Franklin left the hood and I would have loved some repo missions for him, all that went by way too fast.
And it's hard to explain but I didn't really feel the flow of the story mode. I did enjoy it but not as much as I enjoyed RDR to be honest. I really started to miss the things IV, RDR and MP3 did have, the little things that amount to a lot really.
One interesting thing about that is I think it varies drastically for people... for me, Franklin spent a huge portion of the game time on Forum Drive because I did so much exploring at the start. I tried to take my time and do free roam stuff at the start before the story picked up much urgency -- felt it made more sense to go explore and mess around while in the middle of casual repo jobs and before M's story really picked up.
Anecdote aside, reason I say it seems to vary drastically for people (and not just my unique anecdote) is because based on Trophy data, something like only 30 or 35% of GTA5 players have even reached Trevor. Basically 2/3rds of GTA5 owners never even played Trevor before and still have Franklin living in his mom's house. So I think for a lot of folks, even though you can reach that first 'get rich' point pretty fast if you focus on the story, quite a lot of people never actually do that, and just free roam a lot.
The game has such a huge amount of story-sensitive content, phone calls, character switch scenes, etc, that it's almost a detriment to 'getting the most out of the game' if you don't free roam a fair bit in between each missions.