To be honest, if RE7 is horror themed, I'm wondering how they'll tackle it.
There is no way in hell it's one of those defenseless/hiding horror games, the RE series has always had gunplay, and there is absolutely no reason anyone should expect it to be going away (nor would I or many people want it to).
I also personally think there's no way it's a fixed camera angle 'classic-styled' survival-horror game, like some purists seem to want it to be. REmake 2 might be these (and I do hope it is, personally), but RE7? No way.
That said, I'm not convinced it's going to be an over-the-top action title either. I don't think Capcom is bluffing in all they've said over the last three years that for RE7 they have seriously been considering trying the horror route again, and the recent rumors, and even their E3 area, does heavily suggest they want to make a game that one is best to play in the dark with headphones.
I actually think without knowing what the next game is yet, it's one of the hardest times for me to be a fan of both the older and newer RE games. Half of me wants this to be a horror game, to be a more serious attempt at making something horror for the series in the first time in a numbered entry for years. The other half of me doesn't want RE's fun gunplay, co-op, and things like Mercenaries to go anywhere.
I think it is possible to make a RE game that is both things, just not an easy task. Then again, I think it's possible to make a good horror co-op game, just no one has outright done it yet. Ironically, the closest attempt to something like this was the RE series, with the Outbreak games. I'm actually wondering if Capcom have been looking to Outbreak for some inspiration for RE7, I've noticed they've been mentioning Outbreak a lot more recently. That could be about the HD Remaster rumor, but maybe also they looked to Outbreak as their example of a horror/co-op game, and how they may modernize it in certain areas, is a thought.
We'll probably see RE7 tomorrow, and I look forward to it. A big part of me thinks that RE7 may be trying to reinvent the wheel again, like what they did for RE4, and maybe attempted again with RE6, but in a more distinct direction. I expect that shooting and gunplay may still be big parts, but maybe it's going to try and be a lot more atmospheric and deal with less 'mob' enemy types we've seen in RE games recently, and more big and powerful entities that are a serious danger, is a thought of mine. Maybe it'll be Zombie haven though, or maybe they'll decide to go in some other unexpected direction.
I think this RE game announcement is one of the most interesting in years partially because right now, it could really go anyway. After RE4's success, it was obvious they were going to make another entry like that, and after RE5's success, it was obvious the next game was going to be an action co-op game. I think RE7 is the first time in a decade it's not been immediately clear what direction Capcom is going with the franchise. They've been surprisingly tight-lipped about it.