About the characters, here's some random ideas...
I'd like to see Chris recruiting new people into the BSAA. That could be how the tutorial of the game is set up, training new people. At the same time, Barry makes a cameo and he's now retired, with his wife passed on and his children all grown up. I'd also like to see him running a bar, for some reason, lol. He talks to Chris about retiring and settling down with Jill, to which Chris says they're just partners. That said, I really don't want some melodramatic plot line, but just some subtle nods about their partnership.
Have Chris trying to recruit Jake into the BSAA and attempting to help him out with the direction of his life, to which Jake shows no interest, as he prefers doing the solo act.
Eventually in the storyline we'll encounter
who's trying to bring back Albert using the C-virus, the same way it was used on
. Near the end of the game, Jake has to make a choice between what Chris is telling him and reuniting with his father. That being said, I don't want Wesker back, just the plot that would create some drama. In the epilogue, have Jake join the BSAA with Chris in a mentor position.
As for Leon and Ada, I'd like to see them hook up, but ultimately she either dies or moves on completely. Because honestly, I don't see her as the type of character who would settle down. Leon should move on to Helena or Claire or someone new.
It's hard to say where all the other characters would fit in, but I figure most could either be brought into the BSAA or given small cameos. For instance, put Carlos in the BSAA along with Sherry (can't see her going back to her organization after Simmons) and bring back Rebecca in a support role like Hunnigan is for Leon.
So yeah, I feel dirty after posting all that.