Big DR2 spoilers - I decided to rank each character by how interesting I think they would be living a long time in a total plot redo:
1. Twogami/Imposter - Obviously. I can't imagine ranking anyone else #1. The idea behind this guy is fascinating but we don't learn shit about him. If 2x2 doesn't feature this guy heavily I'm going to question why the hell they're even doing this.
2. Mahiru - Out of the people who die early in DR2, she's the most likeable and would be the nicest to have around, imo. If we're going to do a protagonist swap, she's the only one who really fits. I feel like sentiment towards her has warmed over time.
3. Peko - Quietly had loads of potential. She died so Fuyuhiko could get a character arc - but it could have easily been the other way around, and I EXPECT it to be the other way around. Besides the Imposter, this feels like one of the more obvious character arcs to turn on its head by having a different character live.
4. Hiyoko - I'll die on this hill! She got done dirty. She was on the verge of having a character arc and got ganked before it could happen. You only like Fuyuhiko because he got redeemed and had a character arc! Give her a chance!
5. Chiaki - Just the simple fact of her being alive at all is going to imbue this game with a lot of tension, because you already know what her story is, and the game knows that you know, so you know they're going to have to switch it up with her but you won't know how. Besides, she's the most popular character in the game and arguably the most popular in the series, so it makes sense to have her stick around.
6. Nagito - Probably going to figure into the new plot quite a bit, if I had to guess, since he's sort of like Chiaki where the game's dynamics just wouldn't be the same without him. But I also expect him to be a wildcard. Maybe he won't be openly crazy this time. I don't know! Obviously they're going to do SOMETHING with Nagito, that's just a given, but it's also really hard for him to top what he already did in DR2.
7. Hajime/Izuru - Complete and total wildcard. This ranking only applies if they do a protagonist swap, which I realize is the "predictable" thing to do but it would just be boring to do Hajime again and have the same plot beats. But if Hajime became Izuru early or something, or slipped into more of a Nagito role somehow? I mean, they kinda have to shake it up here SOMEHOW.
8. Teruteru - I'll stand up and defend Teruteru a little bit. Is he a weird, horny pervert who kinda sucks? Yeah! Is he kind of unexpectedly funny in the first trial? I think so! Could that give him further potential? Maybe! I don't know, I'm probably alone on this, but I think the idea of Teruteru surviving for a long time is really funny and kind of surreal. If you want to sell that we're really going down the rabbit hole, having Teruteru live past chapter 1 would be great.