Just my two cents; I hate reboots. Well, there are exceptions of course, but generally, any series I'm REALLY invested in, I would rather see die than see a reboot of. Unless a game has been totally ran into the ground story and character wise, then maybe. But I really don't think Saints Row has been, even a bit. I enjoy the characters, the story, the atmosphere. I want to see where it goes and what happens next.
Even if what happens to the current Saints is explained in pre-game narration and SRV is with a new cast of characters. I'd prefer the former direct continuation, but still. Years of Saints Row story and characters all thrown out so as to reboot it? Fuck that. I'd still check the game out, and honestly figure I'd still enjoy the gameplay, but it just wouldn't be the same, personally.
As for the city size, I'd like to see a bigger city, but I'd also favor more playtime and customization. Actually, for city "size," I'd prefer just having more interiors over actual landmass or multiple cities. Though I think 2 or 3 cities could be really fun too possibly. I'm more of a details person I guess.