I think it'd be interesting to see what Claire's been doing. With her work with TerraSave and everything. In a southeast asian country like: Indonesia or the Philippines. And she's paired up with a TerraSave agent of that country or just someone indigenous to the region. Similar to Sheva and the BSAA in Resident Evil 5. Either a guy or girl. It doesn't really matter in my opinion. Just a scenario I had thought up that might be amusing to some.
Also, I think receiving the choice of having a partner and choosing whether or not to play in co-op would be an interesting add-on to Resident Evil 7. Obviously, gameplay between both options will be different and present distinct problems and challenges, but I don't see the problem with that either. So, players who like more of a classic style of gameplay of previous REs and players who enjoy something more on the lines of a cooporative style of experience, will be pleased.
I have no problem with the whole "three different campaigns," concept, but hopefully if they do it in Resident Evil 7, Capcom decides to un-tangle things a bit and not have multiple story-lines clashed together solely for the sense of intrigue. When in reality, it was overly convoluted and forced. But, having key moments of the main cast either meeting up or radio/telecasting would be acceptable and actually affective to the whole general concept of horror that Resident Evil stands for and is all about. Or, Capcom can go in an entirely different direction and go back to a one campaign type of Resident Evil. But, who know to be honest.
As for other character choices for the main story and plot-line, it could go in any direction. Eventhough, I'd like to see Claire, Jill, Rebecca and Carlos' characters reprised. Seeing that the haven't had a game dedicated to them in god knows how long. Hopefully, not having Leon and Chris as main characters would be a breath of fresh air. I think that Capcom needs to either wait a bit to bring them back for a final-go-around or just give them smaller roles in Resident Evil 7. It's been vaguely established that Jake and Ada will appear somewhere in the future. But, this doesn't necessarily mean they'll make a cameo in Resident Evil 7. Just what I think honestly. But, I wouldn't mind it.
Finally, the game mechanic and controls for Resident Evil 7 will be interesting to see because from what's been done, you really can't pin-point where it'll go from here. I personally think the whole third person motif is here to stay. It doesn't really bother me, but I'm sure Capcom will do something to freshen things up. Example: CQC abilities in recent REs. So, it's really unclear.
There is still much to be said about what can and shouldn't be done or added to Resident Evil 7, but I'll still play it no matter what. I've been here since the start and enjoy old and new REs alike.