I'll try to talk about the things I want without bashing it too much on the game, because I know it gets old. I don't like CVX, never did. Not the story only. Gameplay was a step back from RE3, voice acting is all over the place and so on...anyway.
To me the first thing to fix would be pacing. CV's pacing is HORRIBLE. Some of the worst in the series. You spend too much time walking to one side to the other of an empty map, because you killed everything already (CV has tons of ammo). I'm not worried too much about this, because on my opinion RE2R and RE3R have good pace. I suppose a remake of CV would have the slow pace of RE2R, and it would be fine.
I don't mind the change of scenery . Unlike most people, I find CV's locations to be okay-ish at best. The best place is the Ashford Manor. Training Center is alright. Antartica Research Base is forgettable for the most part. I'm really hoping for a map revamp though. Maybe a better plan on locations to eliminate the unecessary backtracking and running through empty corridors. Also, maybe changing the layout a bit so Chris could explore more new areas, instead of running through the same place as Claire, but with half of the scenario destroyed.
Like it was said before, I'm pretty sure the Ashfords will be changed in some capacity, maybe to make them feel less Disney villains and I'm all for it, since I dislike both Ashfords as they're portrayed in the original. Maybe a good place to start brainstorming would be Darkside Chronicles's Game of Oblivion. I like Alfred a lot in this game, being a complete psycho, unlike the utter failure he is in the original game. Also, DC does a better Steve, so this will always be a plus. I'm also not worried about voice acting anymore, since Capcom has sorted this out a long time ago (Revelations 1 is a bump in the way though. Weird voice acting all around in that game).
I don't think we need new monsters, since CV already has a good number of them. I expect RE3's hunters to be back, which is terrifying and exciting and I'm can only think they'll make Bandersnatches look even more gross and dangerous. Also, CV has a giant spider as a boss, so I think we'll finally see spiders as enemies in a modern remake?
Anyway, If I would choose between a remake of CV and 4, I would choose CV without thinking. Let's hope someone at Capcom can push this foward in the future.